| 1. |
- Adachi, N., et al.
(författare)
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Epitaxial Bi3Fe5O12(001) films grown by pulsed laser deposition and reactive ion beam sputtering techniques
- 2000
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 88:5, s. 2734-2739
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Tidskriftsartikel (refereegranskat)abstract
- We report on processing and comparative characterization of epitaxial Bi3Fe5O12 (BIG) films grown onto Gd-3(ScGa)(5)O-12[GSGG,(001)] single crystal using pulsed laser deposition (PLD) and reactive ion beam sputtering (RIBS) techniques. A very high deposition rate of about 0.8 mu m/h has been achieved in the PLD process. Comprehensive x-ray diffraction analyses reveal epitaxial quality both of the films: they are single phase, exclusively (001) oriented, the full width at half maximum of the rocking curve of (004) Bragg reflection is 0.06 deg for PLD and 0.05 deg for RIBS film, strongly in-plane textured with cube-on-cube film-to-substrate epitaxial relationship. Saturation magnetization 4 pi M-s and Faraday rotation at 635 nm were found to be 1400 Gs and -7.8 deg/mu m in PLD-BIG, and 1200 Gs and -6.9 deg/mu m in RIBS-BIG. Ferromagnetic resonance (FMR) measurements performed at 9.25 GHz yielded the gyromagnetic ratio gamma=1.797x10(7) l/s Oe, 1.826x10(7) l/s Oe; the constants of uniaxial magnetic anisotropy were K-u(*)=-8.66x10(4) erg/cm(3), -8.60x10(4) erg/cm(3); the cubic magnetic anisotropy K-1=-2.7x10(3) erg/cm(3),-3.8x10(3) erg/cm(3); and the FMR linewidth Delta H=25 and 34 Oe for PLD and RIBS films correspondingly. High Faraday rotation, low microwave loss, and low coercive field less than or equal to 40 Oe of BIG/GSGG(001) films promise their use in integrated magneto-optic applications.
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| 2. |
- Ansari, Nazanin, et al.
(författare)
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Multicolor filter all-garnet magneto-optical photonic crystals
- 2012
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 37:17, s. 3552-3554
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a multicolor optical filter and isolator based on a double-cavity magneto-optical (MO) photonic crystal. Being grown as a heteroepitaxial all-garnet multilayer, it compromises a strong MO response and high optical transmittance. Low-loss, high Faraday rotation passbands as well as strong light rejection within the stop band were achieved by optimization of distance between cavities and repetition number of distributed Bragg reflectors.
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| 3. |
- Balinsky, Michael, et al.
(författare)
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Spin Pumping and the Inverse Spin-Hall Effect via Magnetostatic Surface Spin-Wave Modes in Yttrium-Iron Garnet/Platinum Bilayers
- 2015
-
Ingår i: IEEE Magnetics Letters. - 1949-307X .- 1949-3088. ; 6:3000604
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Tidskriftsartikel (refereegranskat)abstract
- Spin pumping at a boundary between a yttrium-iron garnet (YIG) film and a thin platinum (Pt) layer is studied under conditions in which a magnetostatic surface spin wave (MSSW, or Damon-Eshbach mode) is excited in YIG by a narrow strip-line antenna. It is shown that the voltage created by the inverse spin-Hall effect (ISHE) in Pt is strongly dependent on the wavevector of the excited MSSW. For YIG film thicknesses of 41 and 0.9 mu m, the maximum ISHE voltage corresponds to the maximum of efficiently excited MSSW wavevectors and does not coincide with the maximum of absorbed microwave power. For a thinner (0.175 mu m) YIG film, the maximum of the ISHE voltage moves closer to the ferromagnetic resonance and almost coincides with the region of the maximum microwave absorption. We show that the effect is related to the change in the thickness profile and the wavenumber spectrum of the excited MSSW taking place when the YIG film thickness is increased.
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| 4. |
- Belotelov, V. I., et al.
(författare)
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Magnetophotonic intensity effects in hybrid metal-dielectric structures
- 2014
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:4, s. 045118-
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Tidskriftsartikel (refereegranskat)abstract
- The magneto-optical properties of a hybrid metal-dielectric structure consisting of a one-dimensional gold grating on top of a magnetic waveguide layer are studied experimentally and theoretically. It is demonstrated that a magnetic field applied in the longitudinal configuration (in the plane of the magnetic film and perpendicular to the slits in the gold grating) to the metal-dielectric structure modifies the field distribution of the optical modes and thus changes the mode excitation conditions. In the optical far field, this manifests in the alteration of the optical transmittance or reflectance when the structure becomes magnetized. This magneto-optical effect is shown to represent a novel class of effects related to the magnetic-field-induced modification of the Bloch modes of the periodic hybrid structure. That is why we define this effect as "longitudinal magnetophotonic intensity effect" (LMPIE). The LMPIE has two contributions, odd and even in magnetization. While the even LMPIE is maximal for the light polarized perpendicular to the grating slits (TM) and minimal for the orthogonal polarization (TE), the odd LMPIE takes maximum values at some intermediate polarization and vanishes for pure TM and TE polarizations. Two principal modes of the magnetic layer - TM and TE - acquire in the longitudinal magnetic field additional field components and thus turn into quasi-TM and quasi-TE modes, respectively. The largest LMPIE is observed for excitation of the antisymmetrical quasi-TE mode by TM-polarized light. The value of the LMPIE measured for the plasmonic structure with a magnetic film of Bi2Dy1Fe4Ga1O12 composition is about 1% for the even effect and 2% for the odd one. However, the plasmonic structure with a magnetic film with a higher concentration of bismuth (Bi2.97Er0.03Fe4Al0.5Ga0.5O12) gives significantly larger LMPIE: even LMPIE reaches 24% and odd LMPIE is 9%. Enhancement of the magneto-optical figure of merit (defined as the ratio of the specific Faraday angle of a magnetic film to its absorption coefficient) of the magnetic films potentially causes the even LMPIE to exceed 100% as is predicted by calculations. Thus, the nanostructured material described here may be considered as an ultrafast magnetophotonic light valve.
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| 5. |
- Belotelov, V. I., et al.
(författare)
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Plasmon-mediated magneto-optical transparency
- 2013
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 4, s. 2128-
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic field control of light is among the most intriguing methods for modulation of light intensity and polarization on sub-nanosecond timescales. The implementation in nanostructured hybrid materials provides a remarkable increase of magneto-optical effects. However, so far only the enhancement of already known effects has been demonstrated in such materials. Here we postulate a novel magneto-optical phenomenon that originates solely from suitably designed nanostructured metal-dielectric material, the so-called magneto-plasmonic crystal. In this material, an incident light excites coupled plasmonic oscillations and a waveguide mode. An in-plane magnetic field allows excitation of an orthogonally polarized waveguide mode that modifies optical spectrum of the magneto-plasmonic crystal and increases its transparency. The experimentally achieved light intensity modulation reaches 24%. As the effect can potentially exceed 100%, it may have great importance for applied nanophotonics. Further, the effect allows manipulating and exciting waveguide modes by a magnetic field and light of proper polarization.
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| 6. |
- Blomqvist, Mats, et al.
(författare)
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Electro-optic effect in ferroelectric Na0.5K0.5NbO3 thin films on oxide substrates
- 2006
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Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 80:1, s. 97-106
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Tidskriftsartikel (refereegranskat)abstract
- We have deposited Na0.5NbO3 (NKN) films oil single crystal Al2O3(1 (1) under bar 02) and SrTiO3(001) substrates using rf-magnetron sputtering of a stoichiometric, high-density ceramic target. Using x-ray diffraction it was confirmed that NKN grows preferentially c-axis oriented on sapphire substrate and epitaxially oil the perovskite SrTiO3(001) substrate. Electro-optical (EO) properties were measured in visible light through a transverse method. With an applied dc field up to 20 kV/cm, the effective linear EO response was determined to r(eff) = 28 pm/V for NKN/Al2O3 and r(eff) = I I pm/V for NKN/SrTiO3, where a superlinear dependence was observed.
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| 7. |
- Blomqvist, Mats, et al.
(författare)
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Electrooptic ferroelectric Na0.5K0.5NbO3 films
- 2005
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 17:8, s. 1638-1640
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Tidskriftsartikel (refereegranskat)abstract
- We report on waveguiding and electrooptic properties of epitaxial Na0.5K0.5NbO3 films grown by radio-frequency magnetron sputtering on Al2O3 (1102) single crystal substrates. High optical waveguiding performance has been demonstrated in infrared and visible light. The in-plane electrooptic effect has been recorded in transmission using a transverse geometry. At dc fields, the effective linear electrooptic coefficient was determined to 28 pm/V, which is promising for modulator applications.
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| 8. |
- Blomqvist, Mats, et al.
(författare)
-
High-performance epitaxial Na0.5K0.5NbO3 thin films by magnetron sputtering
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:2, s. 337-339
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial Na0.5K0.5NbO3 (NKN) thin films have been grown on LaAlO3 substrates by rf magnetron sputtering of a stoichiometric, high-density, ceramic target. X-ray diffraction analysis showed c-axis oriented cube-on-cube growth. Micrometer size interdigital capacitor (IDC) structures were defined on the surface of the NKN film using photolithography. The electrical characterization at 1 MHz showed dissipation factor tan delta of 0.010, tunability 16.5% at 200 kV/cm and dielectric permittivity epsilon(r)=470. The frequency dispersion of epsilon(r) between 1 kHz and 1 MHz was 8.5% and the IDCs showed very good insulating properties with leakage current density on the order of 30 nA/cm(2) at 400 kV/cm. The polarization loop exhibits weak ferroelectric hysteresis with maximum polarization 23.5 muC/cm(2) at 600 kV/cm. These results are promising for tunable microwave devices based on rf sputtered NKN thin films.
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| 9. |
- Blomqvist, Mats, et al.
(författare)
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Optical waveguiding in magnetron-sputtered Na0.5K0.5NbO3 thin films on sapphire substrates
- 2003
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:3, s. 439-441
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Tidskriftsartikel (refereegranskat)abstract
- Preferentially oriented perovskite-structured Na0.5K0.5NbO3 (NKN) thin films have been deposited on hexagonal Al2O3(01 (1) under bar2) substrates using rf magnetron sputtering of a stoichiometric, high-density, ceramic target. Structural and film surface properties were measured using x-ray diffraction and atomic force microscopy, respectively. Optical and waveguiding properties were characterized using a prism-coupling technique. We observed sharp and distinguishable TM and TE propagation modes and measured the refractive index of NKN thin films of different thicknesses. The ordinary and extraordinary refractive indices were calculated to be n(o)=2.247+/-0.002 and n(e)=2.216+/-0.002 for a 2.0-mum-thick film at 632.8 nm. This implies a birefringence Deltan=n(e)-n(o)=-0.031+/-0.002 in the film. These first results show the potential use of rf-sputtered NKN films as an electro-optical active material.
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| 10. |
- Blomqvist, Mats, et al.
(författare)
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Rf-magnetron sputtered ferroelectric (Na,K)NbO3 films
- 2002
-
Ingår i: Proceedings of the 13th IEEE International Symposium on Applications of Ferroelectronics. - 0780374142 ; , s. 195-198
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Konferensbidrag (refereegranskat)abstract
- Sodium potassium niobate (Na,K)NbO3 (NKN) thin films were grown by rf-magnetron sputtering from stoichiometric Na0.5K0.5NbO3 target on LaAlO3 (LAO) single crystals and polycrystalline Pt80Ir20 (PtIr) substrates. NKN films on polycrystalline PtIr substrates were found to be preferentially (004 oriented while XRD measurements reveal epitaxial quality of NKN/LaAlO3 film structures. The ferroelectric state in NKN/PtIr films at room temperature is indicated by polarization loops with polarization as high as 33.4 muC/cm(2) at 700 kV/crn, remnant polarization of 9.9 muC/cm(2), and coercive field of 91 kV/cm. I-V characteristics of vertical Au/NKN/PtIr capacitive cells and planar Au/NKN/LAO interdigital capacitors (IDCs) showed very good insulating properties. For NKN IDC the leakage current density was in the order of 30 nA/cm(2) at 400 kV/cm. Rf dielectric spectroscopy demonstrates low loss, low frequency dispersion, and high voltage tunability both for vertical Au/NKN/PtIr and planar interdigital Au/NKN/LAO capacitors.
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| 11. |
- Blomqvist, Mats, et al.
(författare)
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Rf sputtered Na0.5K0.5NbO3 films on oxide substrates as optical waveguiding material
- 2003
-
Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 54, s. 631-640
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Tidskriftsartikel (refereegranskat)abstract
- Highly crystalline Na0.5K0.5NbO3 (NKN) thin films of 1-2 mum thickness were deposited by rf-magnetron sputtering of a stoichiometric, ceramic target on single crystal LaAlO3 (001) and Al2O3 (01 (1) under bar2) substrates. X-ray diffraction measurements revealed epitaxial quality of NKN/LaAlO3 film structures, whereas NKN films on sapphire substrates were found to be preferentially c -axis oriented. A prism-coupling technique was used to characterize optical and waveguiding properties. A bright-line spectrum at lambda = 632.8 nm, revealed sharp peaks, corresponding to transverse magnetic (TM) and electric (TE) waveguide propagation modes in NKN/LaAlO3 and NKN/Al2O3 thin films. Using a least mean square fit the refractive index for the films and film thickness were calculated. The extraordinary and ordinary refractive indices were determined to n(e) = 2.207 +/- 0.002 and n(o) = 2.261 +/- 0.002, and n(e) = 2.216 +/- 0.002 and n(o) = 2.247 +/- 0.002 at lambda = 632.8 nm for 2.0 mum thick NKN films on LaAlO3 and Al2O3 , respectively. This corresponds to a birefringence Deltan = n(e) - n(o) = -0.054 +/- 0.003 and Deltan = -0.031 +/- 0.003 in the films, where the larger Deltan for the NKN/LaAlO3 structure can be explained by the superior crystalline quality compared to NKN/Al2O3 . Atomic force microscopy images of the film surfaces revealed rms roughnesses of 2.5 nm and 8.0 nm for 1.0-mum thick NKN/LaAlO3 and NKN/Al2O3 films, respectively. We believe surface scattering is one of the main sources of waveguide losses in the thin films.
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| 12. |
- Blomqvist, Mats, et al.
(författare)
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Visible and IR light waveguiding in ferroelectric Na0.5K0.5NbO3 thin films
- 2005
-
Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 69, s. 277-286
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Tidskriftsartikel (refereegranskat)abstract
- High-quality ferroelectric thin films are attractive materials for integrated optics applications including electro-optic waveguide modulators and frequency doubling secondharmonic generators. Several fefroelectric thin film materials, such as BaTiO3, KNbO3, LiNbO3, and (Pb,La)(ZrTi)O-3, have been investigated regarding their optical and waveguiding properties. Recently the first results on waveguiding in ferroelectric Na0.5K0.5NbO3 (NKN) thin films were presented. Perovskite NKN films have previously been investigated as electrically tunable material for low loss rf and microwave applications. Na0.5K0.5NbO3 thin films of thickness 0.5-1.0 mum have been deposited on Nd:YAlO3(001) and Al2O3(0112) substrates using rf-magnetron sputtering of a stoichiometric, high-density ceramic target. X-ray diffraction measurements confirmed films grown highly (00l) oriented on the perovskite Nd:YAlO3 substrate and preferentially c-axis oriented on the single crystal r-cut sapphire substrate. Optical and waveguiding properties were characterized using a Metricon 2010 prism-coupling apparatus with a rutile prism. Dark-line spectra were obtained at visible light (lambda = 632.8 nm) as well as at infrared optical communication wavelengths, lambda = 1319 nm and lambda = 1549 nm, in both transverse electric (TE) and transverse magnetic (TM) polarizations. Sharp dips corresponding to waveguide propagation modes in the thin film layers where observed for both substrates. The calculated refractive index values and corresponding birefringence (Deltan = n(TM) - n(TE) = n(e) - n(o)) as a function of wavelength has been compared. Generally a larger birefringence is observed for the NKN film on Nd:YAlO3, which is in agreement with the larger degree of preferential c-axis orientation measured by XRD.
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| 13. |
- Bonetti, Stefano, et al.
(författare)
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Buried tantalate-niobate microwave varactors
- 2007
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Ingår i: 2006 15TH IEEE INTERNATIONAL SYMPOSIUM ON APPLICATIONS OF FERROELECTRICS. - 9781424413317 ; , s. 347-350
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Konferensbidrag (refereegranskat)abstract
- We present characteristics of microwave variable capacitors (varactors) buried in 2.5 mu m thick AgTa0.5Nb0.5O3 (ATN) film pulsed laser deposited on sapphire single crystal. 2 gm gap interdigital capacitors (IDC) were fabricated by photolithographic, dry etching and lift-off processes. For comparison, similar IDCs were also defined on top of ATN film. Capacitance and loss tangent have been determined using a modified de-embedding technique in the microwave range 25 MHz - 40 GHz. Buried structures show higher values of capacitance and tunability, keeping the same level of losses compared to standard topped devices and resulting in an increased K-factor = tunability/tan delta. Experimental results are explained within equivalent circuit model. Besides the increased performance, the new design avoids the need of a successive planarization step, which could be required in an integration process.
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| 14. |
- Brunahl, J., et al.
(författare)
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Non-destructive pulsed technique to characterize functional properties of micromachined bulk PZT
- 2001
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Ingår i: Ferroelectrics (Print). - 0015-0193 .- 1563-5112. ; 263:1-4, s. 1487-1492
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Tidskriftsartikel (refereegranskat)abstract
- In this report, a non-destructive pulsed technique is presented to characterize all relevant properties of machined bulk PZT material. The proposed method is based on recording of the transient current as response on the short voltage pulse applied to the ferroelectric acoustic element. This new promising experimental technique makes it possible to measure mechanical and electrical properties fast, reliably and reproducibly. Among other results we can obtain electromechanical coupling coefficient, dielectric loss factor tan 8, mechanical quality factor Q, dielectric constant, capacitance, resonant frequency and Curie temperature T-c. The temperature dependence of above mentioned parameters can be studied as well very easily.
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| 15. |
- Dyakonov, V., et al.
(författare)
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Spin-wave resonance in the La0.7Mn1.3O3-delta film
- 2000
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Ingår i: Physics Letters A. - 0375-9601 .- 1873-2429. ; 268:3, s. 202-207
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Tidskriftsartikel (refereegranskat)abstract
- The spin-wave resonance (SWR) spectra have been observed in the (001) oriented La0.7Mn1.3O3-delta epitaxial films. The spectra consist of a series of well-resolved spin-wave modes clearly seen in the: perpendicular external field configuration. It is shown that the spins are completely pinned on both sides of the film surface. Based on a study of the SWR spectra the value of the spin-wave exchange constant, D, is found to be 150 meV Angstrom(2). This value of. D correlates well with this one determined for all known until now manganites.
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| 16. |
- Ekström, Mattias, et al.
(författare)
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Integration and High-Temperature Characterization of Ferroelectric Vanadium-Doped Bismuth Titanate Thin Films on Silicon Carbide
- 2017
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Ingår i: Journal of Electronic Materials. - : SPRINGER. - 0361-5235 .- 1543-186X. ; 46:7, s. 4478-4484
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Tidskriftsartikel (refereegranskat)abstract
- 4H-SiC electronics can operate at high temperature (HT), e.g., 300A degrees C to 500A degrees C, for extended times. Systems using sensors and amplifiers that operate at HT would benefit from microcontrollers which can also operate at HT. Microcontrollers require nonvolatile memory (NVM) for computer programs. In this work, we demonstrate the possibility of integrating ferroelectric vanadium-doped bismuth titanate (BiTV) thin films on 4H-SiC for HT memory applications, with BiTV ferroelectric capacitors providing memory functionality. Film deposition was achieved by laser ablation on Pt (111)/TiO2/4H-SiC substrates, with magnetron-sputtered Pt used as bottom electrode and thermally evaporated Au as upper contacts. Film characterization by x-ray diffraction analysis revealed predominately (117) orientation. P-E hysteresis loops measured at room temperature showed maximum 2P (r) of 48 mu C/cm(2), large enough for wide read margins. P-E loops were measurable up to 450A degrees C, with losses limiting measurements above 450A degrees C. The phase-transition temperature was determined to be about 660A degrees C from the discontinuity in dielectric permittivity, close to what is achieved for ceramics. These BiTV ferroelectric capacitors demonstrate potential for use in HT NVM applications for SiC digital electronics.
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| 17. |
- Emmoth, Birger, et al.
(författare)
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Fuel removal from bumper limiter tiles by using a pulsed excimer laser
- 2005
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 337-39:1-3, s. 639-643
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Tidskriftsartikel (refereegranskat)abstract
- Samples of a limiter tile from the TEXTOR tokamak were investigated by scanning electron microscopy and nuclear reaction analysis both before and after laser heating. SEM images showed spheres and thin flakes covering the surface which are the areas modified by plasma particles striking under grazing angles. Due to roughness of the surface there are shadowed regions between the 'flakes'. Laser pulses did not lead to expected common ablation of the surface. Features that looked like 'melting' of thin surface layers were rather observed. The initial deuterium content in the surface layer of tiles was of the order of 10(18) D atoms per cm(2). After the laser light impact the content decreased with 60-70%; by reducing the deposited power by a factor four, the deuterium content was decreased by 40-50%. We make the interpretation that we approach a threshold of the laser detritiation method in fusion devices.
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| 18. |
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| 19. |
- Fors, R., et al.
(författare)
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Giant resistance switching in metal-insulator-manganite junctions : Evidence for Mott transition
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 71:4
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Tidskriftsartikel (refereegranskat)abstract
- Heteroepitaxial CeO2(80 nm)/L0.67Ca0.33MnO3(400 nm) film structures have been pulsed laser deposited on LaAlO3(001) single crystals to fabricate two terminal resistance switching devices. Ag/CeO2/L0.67Ca0.33MnO3 junctions exhibit reproducible switching between a high resistance state (HRS) with insulating properties and a semiconducting or metallic low resistance state (LRS) with resistance ratios up to 10(5). Reversible electrical switching is a polar effect achievable both in continuous sweeping mode and in the pulse regime. Successive temperature crossover of electronic transport from the thermal activation of the deep levels (E-a=320 meV) at high temperatures to thermal activation of the shallow levels (E-a=40 meV) and finally at low temperatures to the regime of temperature independent resistance, usually associated with quantum tunneling, has been found for the insulating HRS. The temperature dependence of the LRS reveals a para-to-ferromagnetic phase transition in the L0.67Ca0.33MnO3 (LCMO) electrode at T-c=260 K and an anomaly at lower temperatures similar to200 K corresponding to the Curie temperature of the Mn4+ depleted part of the LCMO film. Current-voltage characteristics in the LRS are highly nonlinear, and show negative differential conductivity (NDC). We suggest that the reversible resistance switching ocurrs due to the electric field induced nucleation of filament-type conducting valence-shifted CeOx domains inside the insulating CeO2 matrix. The abrupt insulator-to-metal transition is the result of localization of 4f electronic states in Ce3+ ions and the subsequent appearance of hole conductivity in the oxygen p-bands. NDC at low temperatures is relied upon the interband scattering of CeOx carriers from a low energy, high mobility valley into a high energy valley with low mobility.
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| 20. |
- Fors, Rickard, et al.
(författare)
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Non-volatile giant resistance switching in metal-insulator-manganite junctions
- 2005
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Ingår i: Materials and Processes for Nonvolatile Memories. - WARRENDALE : MATERIALS RESEARCH SOCIETY. - 1558997784 ; , s. 379-384
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Konferensbidrag (refereegranskat)abstract
- Heteroepitaxial CeO2(80nm)/L0.67Ca0.33MnO3(400nm) film structures have been pulsed laser deposited on LaAlO3(001) single crystals to fabricate two terminal resistance switching devices. Ag/CeO2/L0.67Ca0.33MnO3 junctions exhibit reproducible switching between a high resistance state (FIRS) with insulating properties and a semiconducting or metallic low resistance state (LRS) with resistance ratios up to 10(5). Reversible electrical switching is a polar effect achievable both in continuous sweeping mode and in the pulse regime.
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| 21. |
- Fors, Rickard, et al.
(författare)
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Sol-gel derived versus pulsed laser deposited epitaxial La0.67Ca0.33MnO3 films : structure, transport and effects of post-annealing
- 2004
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 467:02-jan, s. 112-116:467, s. 112-116
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial La0.67Ca0.33MnO3 films have been prepared on LaAlO3 crystals by pulsed laser deposition (PLD) and by a novel all-alkoxide sol-gel technique. Different out-of-plane lattice parameters are found for the as-prepared films, and scanning electron microscopy shows a more porous structure for sol-gel films as compared to PLD films. These differences are largely removed by post annealing at 1000 degreesC. Transport measurements show maximum temperature coefficient of resistivity of 8.2% K-1 at 258 K (PLD) and 6.1% K-1 at 241 K (sol-gel) and colossal magnetoresistance at 560 kA/m of 35% at 263 K (PLD) and 32% at 246 K (sol-gel).
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| 22. |
- Grishin, Alexander, et al.
(författare)
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All-garnet magneto-optical photonic crystals
- 2008
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Ingår i: Journal of the Magnetics Society of Japan. - Japan. - 1882-2924. ; 32:2, s. 140-145
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Tidskriftsartikel (refereegranskat)abstract
- We survey the properties of all-garnet magneto-optical (MO) heteroepitaxial film structures grown by pulsed laser deposition and rf-magnetron sputtering. 1D MO-photonic crystals (MOPCs) were composed of /4 garnet layers alternating highly gyrotropic B13Fe5O12 (BIG) and MO-passive rare earth gallium garnets. As designed, MOPCs' spectra exhibit optical stop band with the transmittance central peak caused by light localization in /2 thick BIG cavity. The first all-garnet BIG/YIG MOPC showed 140% enhancement of the Faraday rotation (FR) compared to a single layer BIG film [APL 84, 1438 (2004)]. Further improvement of MO-performance has been achieved due to the replacement of optically dense YIG by transparent Gd- (GGG), Sm- and novel La-Ga-garnets [APL 86, 141108 (2005); 87, 122504 (2005); 90, 191113 (2007); JAP 101, 053906 (2007)]. At the resonance wavelengths 750 (980) nm, specific FR F=-20.5 (-7.3) deg/m and MO-quality factor Q = 2 |F| /absorption = 66 (43.6) deg represent the highest MOPC performance achieved so far. Respectively, this is 470 (810) % and 31 (190)% enhancement compared to a single layer BIG. MO-remanence (latching capability) has been engineered in the series of BIG:GGG(n:m) superlattices. Regular alternating of lattice mismatched garnet layers impedes the nucleation of misfit dislocations, preserves a long range coherent compressive strain through the whole multilayer thickness thus results in a strong uniaxial magnetic anisotropy. 2.5 m thick BIG:GGG(3:2) film at 678 nm shows FR=1.4 deg, transmittance 82%, 92% squareness of magnetization loop, saturation and coercive fields as low as 56 and 25 Oe, respectively. Nanostructured garnets were used to build MO-visualizer and current driven MO-display [APL 88, 242504 (2006)].
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| 23. |
- Grishin, Alexander M., et al.
(författare)
-
980 nm Bi3Fe5O12/Sm3Ga5O12 magneto-optical photonic crystal
- 2007
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:19
-
Tidskriftsartikel (refereegranskat)abstract
- Heteroepitaxial all-garnet magneto-optical photonic crystal (MOPC) was fabricated to enhance Faraday rotation at 980 nm. MOPC was composed of alternating MO-active Bi3Fe5O12 and transparent Sm3Ga5O12 quarter-wavelength layers grown by rf-magnetron sputtering on Ca,Mg,Zr:Gd3Ga5O12(111) single crystal substrate. High MO performance at the resonance wavelength lambda=980 nm, specific Faraday rotation theta(F)=-7.3 degrees/mu m, absorption coefficient alpha=3350 cm(-1), and MO figure of merit Q=2 parallel to theta(F)parallel to/alpha=43.6 degrees demonstrates feasibility to use bismuth iron garnet MOPCs for application in pump laser diodes, optical amplifiers, modulators, and sensors.
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| 24. |
- Grishin, Alexander M., et al.
(författare)
-
Epitaxial colossal magnetoresistive/ferroelectric heterostructures on Si
- 2004
-
Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 67, s. 69-76
-
Tidskriftsartikel (refereegranskat)abstract
- We report on processing and properties of La-0.67(SrCa)(0.33)MnO3 (LSCMO) films grown by pulsed laser deposition technique on Si(001) substrates buffered with Bi4Ti3O12/CeO2/YSZ heteroepitaxial layers. X-ray diffraction shows cube-on-cube growth of epitaxial Bi4Ti3O12/CeO2/YSZ/Si heterostructure whereas the LSCMO layer grows in the diagonal-on-side manner onto the Bi4Ti3O12 (BTO) template. High resolution TEM images demonstrate sharp interfaces between the buffer layers and LSCMO film as well as rare misfit dislocations on the CeO2/YSZ interface. LSCMO film processing conditions have been optimized to get maximum temperature coefficient of resistivity TCR = 4.4% K-1 and colossal magnetoresistance (CMR) Deltarho/rho similar to 2.9% kOe(-1) @ 294 K. Almost ultimate CMR performance at room temperature has been achieved due to successive improvement of c-axis orientation of layers: full widths at half-maximum (FWHM) = 0.65, 0.58, 0.65, 1.13 and 0.18 degrees in LSCMO/BTO/CeO2/YSZ/Si stack, respectively. Characterization of electrical noise in CMR film yields Noise Equivalent Temperature Difference (NETD) as low as 1.2 muK/rootHz @ 30 Hz and 294 K.
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| 25. |
- Grishin, Alexander M., et al.
(författare)
-
Epitaxial La-0.67(Sr,Ca)(0.33)MnO3 films on Si for IR bolometer applications
- 2004
-
Ingår i: Integration Of Advanced Micro-And Nanoelectronic Devices-Critical Issues And Solutions. - : Springer Science and Business Media LLC. - 155899761X ; , s. 405-410
-
Konferensbidrag (refereegranskat)abstract
- We report on processing and properties of La-0.67(Sr,Ca)(0.33)MnO3 (LSCMO) films grown by pulsed laser deposition technique on Si(001) substrates buffered with Bi4Ti3O12/CeO2/YSZ heteroepitaxial layers. X-ray diffraction shows cube-on-cube growth of epitaxial Bi4Ti3O12/CeO2/YSZ/Si heterostructure whereas the LSCMO layer grows in the "diagonal-on-side" manner onto the Bi4Ti3O12 (BTO) template. High resolution TEM images demonstrate sharp interfaces between the buffer layers and LSCMO film as well as rare misfit dislocations on the CeO2/YSZ interface. LSCMO film processing conditions have been optimized to get maximum temperature coefficient of resistivity TCR = 4.4%K-1 and colossal magnetoresistance (CMR) Deltarho/rho similar to 2.9%kOe(-1) @ 294K. Almost ultimate CMR performance at room temperature has been achieved due to successive improvement of c-axis orientation of layers: full widths at half-maximum (FWHM) 0.65, 0.58, 0.65, 1.13 and 0.18 degrees in LSCMO/BTO/CeO2/YSZ/Si stack, respectively. Characterization of electrical noise in CMR film yields noise equivalent temperature difference (NETD) as low as 1.2 muK/rootHz @ 30Hz and 294K.
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| 26. |
- Grishin, Alexander M., et al.
(författare)
-
Green and blue magneto-optical photonic crystals
- 2012
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 520:9, s. 3647-3650
-
Tidskriftsartikel (refereegranskat)abstract
- A series of one-dimensional heteroepitaxial all-garnet magneto-optical photonic crystals (MOPCs) were pulsed laser deposited to operate at 550 and 470 nm wavelength. We explored the concept of blue shift of the optical absorption edge of ferric ions by substituting Fe with Ga on the tetrahedral sites as well as Bi and Y, respectively, with Ca and Ce at the dodecahedral coordinated positions. 17-layered [Y2Ce1Fe5O12/Gd3Ga5O12] MOPC with a total thickness of 968 nm demonstrates superior magneto-optical performance: Faraday rotation theta(Fmax) = + 2.0 degrees and transmittance as high as 0.35 at the resonance wavelength of 470 nm.
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| 27. |
- Grishin, Alexander M., et al.
(författare)
-
Highly luminescent garnets for magneto-optical photonic crystals
- 2009
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 95:10
-
Tidskriftsartikel (refereegranskat)abstract
- We compare luminescent properties of several Er-doped garnets as building blocks in all-garnet heteroepitaxial magneto-optical photonic crystals. Pulsed laser deposited La3Ga5O12, Gd3Ga5O12, Y3Fe5O12, and rf-magnetron sputtered Bi3Fe5O12 were chosen to host Er3+ ions on dodecahedral lattice sites. Er substituents with the concentration of 0.5 at. % (0.1 garnet formula units) do not decrease giant Faraday rotation in Bi2.9Er0.1Fe5O12 garnet; meanwhile providing intense room temperature C-band photoluminescence (PL). Fe3+ ion works as a sensitizer for Er resulting in fivefold PL enhancement in iron garnets compared to gallium ones. PL lifetime in gallium garnets is in millisecond range reaching almost 6 ms in Gd2.9Er0.1Ga5O12. We conclude Er substitution in gallium and iron garnet layers used both as Bragg mirrors and microcavities promises magneto-optical photonic crystals to become an active lasing medium.
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| 28. |
- Grishin, Alexander M., et al.
(författare)
-
Low field driven latching-type Bi3Fe5O12/Gd3Ga5O12 magneto-optical display
- 2006
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:24
-
Tidskriftsartikel (refereegranskat)abstract
- Series of heteroepitaxial all-garnet magneto-optical (MO) Bi3Fe5O12n/Gd3Ga5O12m /BIG(n)/GGG(m), n= 1, 2, 3, 4, 5 and m=1 and 2 are the numbers of unit cells) nanostructured multilayers have been sintered by pulsed laser deposition technique. Processing parameters and structure of grown films have been optimized to obtain perpendicular magnetic anisotropy and square hysteresis loop with low coercive and saturation magnetic fields. Regular alternating of lattice mismatched BIG and GGG atomic layers inhibited nucleation of misfit dislocations; thus a long range coherent compressive strain was preserved through the whole thickness of BIG(n)/GGG(m) multilayer stack. 2.5 mu m thick BIG(3)/GGG(2) sample (1200 BIG and 800 GGG unit cells) at lambda= 678 nm shows MO Faraday rotation Phi(F)= +/- 1.4 degrees, transmittance of 82%, attenuation alpha=3400 dB/cm, squareness of magnetization loop (remnant-to-saturation magnetizations ratio) as high as 92%, and saturation and coercive fields as low as 56 and 25 Oe, respectively. MO remanence (latching capability) enables application of nanostructured garnet as a magnetic relief replicator/visualizer and as a material for low power consuming displays.
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| 29. |
- Grishin, Alexander M., et al.
(författare)
-
Luminescent Magneto-Optical Photonic Crystals
- 2012
-
Ingår i: ASIA-PACIFIC INTERDISCIPLINARY RESEARCH CONFERENCE 2011 (AP-IRC 2011). - : IOP Publishing. ; , s. 012007-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We compare luminescent properties of several Er-doped garnet films as building blocks in all-garnet heteroepitaxial magneto-optical photonic crystals: La3Ga5O12, Gd3Ga5O12, Y3Fe5O12, Bi3Fe5O12, and Bi2.97Er0.03Fe4Al0.5Ga0.5O12. Er substituents on the dodecahedral lattice sites do not decrease giant Faraday rotation in Bi3Fe5O12 garnet; meanwhile providing intense room temperature C-band photoluminescence (PL). Fe3+ ion works as a sensitizer for Er resulting in fivefold PL enhancement in iron garnets compared to gallium ones. PL lifetime in gallium garnets is in millisecond range reaching 6 ms in Gd2.9Er0.1Ga5O12. The first luminescent one-dimensional heteroepitaxial all-garnet magneto-optical (MO) photonic crystal was composed from diamagnetic Sm3Ga5O12 and MO-active Bi2.97Er0.03Fe4Al0.5Ga0.5O12 garnet layers by rf-magnetron sputtering on Gd3Ga5O12(111) substrate. Substitution of ferric ions by aluminum and gallium improved transparency and induced perpendicular anisotropy in pure Bi3Fe5O12. Photonic crystals owned a record high magneto-optical quality and a latching type (magnetic remnant) Faraday rotation (FR). At the resonance wavelength 775 nm, specific FR theta(F) = -14.1 deg/mu m and MO-quality factor Q = 99.3 deg represent the highest MO performance achieved so far. Long-lived near-IR luminescence in Er substituted gallium and iron garnet layers used both as Bragg mirrors and microcavities promises magneto-optical photonic crystals to become an active lasing medium.
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| 30. |
- Grishin, Alexander M., et al.
(författare)
-
Strong broad C-band room-temperature photoluminescence in amorphous Er2O3 film
- 2006
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:2
-
Tidskriftsartikel (refereegranskat)abstract
- Photoluminescence with the bandwidth of 45 nm (1523-1568 nm at the level of 3 dB) was observed in amorphous Er2O3 films grown on quartz substrate by pulsed laser ablation of erbium oxide stoichiometric target. Optical transmission spectrum has been fitted to Swanepoel formula [J. Phys. E 16, 1214 (1983)] to determine dispersion of refractive index and to extract resonance absorption peaks at 980 and 1535 nm. The maximum gain coefficient as high as 800 dB/cm at 1535 nm was estimated using McCumber theory and experimental spectrum of the resonance absorption. For 5 mm long waveguide amplifier with erbium doping confinement factor of 0.1, the theory predicts the spectral gain of 18 dB with 1.2 dB peak-to-peak flatness in the bandwidth of 31 nm (1532-1563 nm) when 73% of Er3+ ions are excited from the ground state to the I-4(3/2) laser level. Strong broadband photoluminescence at room temperature and inherently flat spectral gain promise Er2O3 films for ultrashort high-gain optical waveguide amplifiers and integrated light circuits.
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| 31. |
- Grishin, Michael A., et al.
(författare)
-
High performance films of binary system SrTiO3-PbZr0.52Ti0.48O3 on sapphire
- 2001
-
Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 39:1-4, s. 351-358
-
Tidskriftsartikel (refereegranskat)abstract
- Continuous series of solid solutions x.SrTiO3-(1-x).PbZr0.52Ti0.48O3 (SPZT) have been grown by pulsed laser deposition technique onto La0.7Sr0.3CoO3/Al2O3(01 (1) under bar2) single crystal. Films properties have been characterized in Au/SPZT/La0.7Sr0.3CoO3(LSCO)/Al2O3 vertical capacitive cell. X-ray diffraction shows SPZT/LSCO bilayer grows in strict epitaxial relationship with sapphire substrate: (001) SPZT parallel to (001) LSCO parallel to (01 (1) under bar2) Al2O3; [010] SPZT parallel to [010] LSCO parallel to [421] Al2O3. LSCO layer was found to be tensile strained, while SPZT film experiences tetragonal distortions c/a -1 approximate to 0.86% which are much lower than 2.73% in pure PZT ceramics. Curie temperature in SPZT film has been tailored continuously in the explored temperature range 77 K to 400 K by controlling SrTiO3:PZT ratio. Processing parameters have been optimized to get the highest tunability factor K = epsilon'(0) - epsilon'(V)/epsilon'(0) x 1/tandelta . SrTiO3:PZT=83:17 film exhibits superior properties: at I kHz maximum dielectric perinittivity and minimum loss tandelta were found to be 870 and 0.005, respectively; while K-factor exceeds value of 60 in the temperature range 280 to 350 degreesC reaching the maximum value of 64 at 325 degreesC. SPZT films can withstand prolonged pre-breakdown electric field and has resistivity as high as 3.5 10(12) Omega cm at 186 kV/cm.
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| 32. |
- Haidar, Mohammad, et al.
(författare)
-
Controlling Gilbert damping in a YIG film using nonlocal spin currents
- 2016
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 94:18
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the control of Gilbert damping in 65-nm-thick yttrium iron garnet (YIG) films using a spin-polarized current generated by a direct current through a nanocontact, spin filtered by a thin Co layer. The magnetodynamics of both the YIG and the Co layers can be excited by a pulse-modulated microwave current injected through the nanocontact and the response detected as a lock-in amplified voltage over the device. The spectra show three clear peaks, two associated with the ferromagnetic resonance (FMR) in each layer, and an additional Co mode with a higher wave vector proportional to the inverse of the nanocontact diameter. By varying the sign and magnitude of the direct nanocontact current, we can either increase or decrease the linewidth of the YIG FMR peak consistent with additional positive or negative damping being exerted by the nonlocal spin current injected into the YIG film. Our nanocontact approach thus offers an alternative route in the search for auto-oscillations in YIG films.
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| 33. |
- Haidar, Mohammad, et al.
(författare)
-
Thickness- and temperature-dependent magnetodynamic properties of yttrium iron garnet thin films
- 2015
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 117:17
-
Tidskriftsartikel (refereegranskat)abstract
- The magnetodynamical properties of nanometer-thick yttrium iron garnet films are studied using ferromagnetic resonance as a function of temperature. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition. First, we found that the damping coefficient increases as the temperature increases for different film thicknesses. Second, we found two different dependencies of the damping on film thickness: at room temperature, the damping coefficient increases as the film thickness decreases, while at T = 8 K, we find the damping to depend only weakly on the thickness. We attribute this behavior to an enhancement of the relaxation of the magnetization by impurities or defects at the surfaces.
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| 34. |
- Hollmark, M., et al.
(författare)
-
Processing and properties of soft magnetic Fe40Co40P14B6 amorphous alloy
- 2001
-
Ingår i: IEEE transactions on magnetics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9464 .- 1941-0069. ; 37:4, s. 2278-2280
-
Tidskriftsartikel (refereegranskat)abstract
- The Fe40Co40P14B6 metallic alloy has been prepared in a glassy state by a melt-spinning process. The 15-25 mum thick as-quenched, ribbons have superior soft magnetic properties compared with those of well-known Fe40Ni40P14B6 glass: the saturation magnetization is about 1.45 T, coercive field 4.0 A/m @ 0.1 Hz, incremental magnetic permeability mu (max) similar to 90 000 @ 60 Hz and Curie temperature above 700 K. The crystallization temperature, determined by differential scanning calorimeter, is approximately 60 K higher than that for FeNi-based alloy, indicating the enhanced thermal stability of FeCo-glass.
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| 35. |
- Jalali-Roudsar, Amir Abbas, et al.
(författare)
-
Determination of magnetic anisotropy constants for magnetic garnet epitaxial films using ferromagnetic resonance
- 2005
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 288, s. 15-21
-
Tidskriftsartikel (refereegranskat)abstract
- The constants of magnetocrystalline anisotropy K-l and uniaxial anisotropy K-u are determined precisely by using ferromagnetic resonance (FMR) and a fitting procedure oil a (1 1 1) yttrium iron garnet (YIG) film made by pulsed laser deposition (PLD) technique. By applying a magnetic field in the azimuthal orientation we introduce measurement in a geometry which yields the anisotropy constants with a high accuracy. The new technique is compared with the previous analysis employing characteristic plane measurements. The new geometry yields at least 15% better accuracy in determining constant K, than by the previous method with FMR.
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| 36. |
- Jalalian, Abolfazl, et al.
(författare)
-
Ferromagnetic resonance in Y(3)Fe(5)O(12) nanofibers
- 2011
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:10, s. 102501-
-
Tidskriftsartikel (refereegranskat)abstract
- Continuous bead-free polycrystalline yttrium iron garnet (YIG) nanofibers 100 mu m long and 50-100 nm in diameter were sintered by sol-gel calcination assisted electrospinning. Room temperature ferromagnetism in YIG fibers is indicated by a well formed M-H hysteresis loop with about 70% of remnant magnetization to the saturated value reached at 150 Oe. Broad band microwave spectroscopy revealed strong asymmetry of ferromagnetic resonance lines that conforms to a three orders of magnitude shape aspect ratio of YIG nanofibers.
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| 37. |
- Johansson, Petter, et al.
(författare)
-
Comparison of Bi3Fe5O12 film giant Faraday rotators grown on (111) and (001) Gd3Ga5O12 single crystals
- 2006
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 515:2, s. 477-480
-
Tidskriftsartikel (refereegranskat)abstract
- Bismuth iron garnet (Bi3Fe5O12, BIG) epitaxial thin films were grown on single crystal (Gd3Ga5O12, GGG) (111) and (001) substrates by rf-magnetron sputtering technique. Processing parameters have been optimized to obtain high deposition rate (2.74 mu m/h) and the surface rms roughness less than 10 nm. X-ray diffraction reveals films epitaxial quality: exclusive (111) or (00 1) orientation with narrow rocking curves and strong in-plane texture. Films possess low optical loss and magneto-optical Faraday rotation (FR) as high as 5 deg/mu m at 677 nm wavelength. Comparative analysis of films grown on (111) and (001) substrates clearly shows significant superiority of BIG/GGG(001) film. For this film, the coercive field similar to 100 Oe appears to be 2.5 times lower while the optical transmission to be 10% higher than that for BIG/GGG(111) film. Enhanced magneto-optical performance of BIG/GGG(001) films relies upon better accommodation of the film-to-substrate mismatch strain through the tetragonal BIG lattice distortions compared to the rhombohedral one in BIG/GGG(111) films.
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| 38. |
- Jonsson, Viktor, et al.
(författare)
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Photoelectron dispersion in metallic and insulating thin films
- 2021
-
Ingår i: Physical Review Research. - : American Physical Society. - 2643-1564. ; 3:3
-
Tidskriftsartikel (refereegranskat)abstract
- The underlying mechanism behind the metal-to-insulator transition in is still a topic of intense debate. The two leading theoretical interpretations associate the transition with either electron-lattice or electron-electron correlations. Novel experimental results are required to converge towards one of the two scenarios. Here we report on a temperature-dependent angle-resolved photoelectron study of thin films across the metal-to-insulator transition. The obtained experimental results are compared to density functional theory calculations. We find an overall energy shift and compression of the electronic band structure across the transition while the overall band topology is conserved. The results demonstrate the importance of electron-electron correlations in establishing the insulating state.
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| 39. |
- Kahl, S., et al.
(författare)
-
Bi3Fe5O12 thin film visualizer
- 2001
-
Ingår i: IEEE transactions on magnetics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9464 .- 1941-0069. ; 37:4, s. 2457-2459
-
Tidskriftsartikel (refereegranskat)abstract
- Micrometer thick Bi-3 Fe-5 O-1.2 (BIG)(001) films were grown onto Gd-3(ScGa)(5)O-12(001) single crystals by the pulsed laser deposition technique. The films are of epitaxial quality with a lattice constant of 1.263 nm. Narrow x-ray rocking curves (full width at half maximum: 0.06 deg) and narrow ferromagnetic resonance lines (widths of 25 Oe) indicate good crystalline quality and magnetic performance. The films possess in-plane magnetization, Faraday rotation as high as -7.8 deg/mum at 630 nm wavelength, and the magnetization M-H curves are linear in the field range from -1.6 kOe to +1.6 kOe. The magneto-optical (MO) properties are almost temperature independent between 5 K and 200 K. This enables the use of thin BIG films as visualizers of magnetic fluxes in high-T-c superconductors. Magnetic fluxes have been visualized in YBa2Cu3O7-infinity, (YBCO) ceramics with an artificial grain boundary. The sensitivity expressed as Faraday rotation angle (per film thickness) per magnetic field unit was found to be 4.9 deg/(kOe . mum) in a 730 nm thick BIG film.
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| 40. |
- Kahl, S., et al.
(författare)
-
Structure, microstructure, and magneto-optical properties of laser deposited Bi3Fe5O12/Gd3Ga5O12(111) films
- 2002
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 91:12, s. 9556-9560
-
Tidskriftsartikel (refereegranskat)abstract
- Bi3Fe5O12 films were deposited onto single crystal Gd3Ga5O12(111) substrates by pulsed laser deposition. X-ray diffraction patterns and cross sectional transmission electron micrographs show epitaxial film growth and a flat interface between the film and substrate. However, there are small inclusions at the interface and a network of cracks is observed by optical microscope. The refractive index is 3.4 at 800 nm wavelength. The optical transmission is low below 540 nm but increases to 90% for a 1.8 mum thick film at 850 nm. The magneto-optical Faraday rotation is high, with a peak value of -24 deg/mum at 560 nm. The angle of Faraday ellipticity reaches a maximum value of 15 deg/mum at 545 nm.
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| 41. |
- Kawasaki, Hiroharu, et al.
(författare)
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TiO2/TiN/TiO2 heat mirrors by laser ablation of single TiN target
- 2008
-
Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 100:1, s. 012038-
-
Tidskriftsartikel (refereegranskat)abstract
- Titanium oxide (TiO2 ) and titanium nitride (TiN) multilayered films grown by pulsed laser deposition (PLD) technique have been tested as a heat mirror, which have a high transmittance in the visible region and a high reflectance in the infrared. Three layer TiO2 /TiN/TiO2 heat mirrors were grown on Corning glass substrates ablating single TiN target. Switching of TiO2 -to-TiN layers composition was achieved by changing gas atmosphere (oxygen-to-nitrogen). Grown TiO2 /TiN/TiO2 heat mirrors are highly transparent in visible (above 60% at 525nm), opaque in infrared (10% at 2600nm) and in the range from 400 nm to 2600 nm they possess almost the same properties as films prepared using two targets: TiO2 and TiN. XPS confirms similarity of chemical composition of multilayered TiO2 /TiN films prepared by single TiN and two TiO2 and TiN targets techniques. Furthermore, multifunctional self cleaning properties of TiO2 /TiN heat mirrors are expected through the precise control of the composition of the top TiO2 layer operating as a photocatalyst.
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| 42. |
- Khartsev, Sergiy, et al.
(författare)
-
Bi3Fe5O12/Gd3Ga5O12 (m) magneto-optical photonic crystals
- 2005
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:12
-
Tidskriftsartikel (refereegranskat)abstract
- A series of one-dimensional heteroepitaxial all-garnet magneto-optical photonic crystals has been synthesized and optically characterized. They are composed of alternating magneto-optically active Bi3Fe5O12 (BIG) and Gd3Ga5O12 (GGG) quarter-wave length layers pulsed laser deposited on to the GGG(001) substrate. Photonic crystals, as designed, exhibit stop band structure and the band gap with the transmittance central peak caused by the light localization in the half-wave length BIG cavity. Compared to previously reported [Bi3Fe5O12/Y3Fe5O12](m) photonic crystal [Appl. Phys. Lett. 84, 1438 (2004)], the replacement of optically dense Y3Fe5O12 garnet by transparent Gd3Ga5O12 enables significant enhancement of light rejection within the stop band. Photonic crystals spectra experience blue shift in oblique incidence geometry thus demonstrating feasibility to use this effect for tunable magneto-optical filters.
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| 43. |
- Khartsev, Sergiy, et al.
(författare)
-
Characterization of heteroepitaxial Na0.5K0.5NbO3/La0.5Sr0.5CoO3 electro-optical cell
- 2005
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:6, s. 062901-1-062901-3
-
Tidskriftsartikel (refereegranskat)abstract
- Heteroepitaxial Na0.5K0.5NbO3(1.5 mum)/La0.5Sr0.5CoO3(0.5 mum) (NKN/LSCO) films were grown on an Al2O3(0112) single crystal (r-cut sapphire) by rf-magnetron sputtering (NKN) and pulsed laser deposition (LSCO) techniques. Prism coupling waveguide refractometry has been employed to characterize vertical capacitive electro-optical cells with 2 X 8 mm(2) semitransparent Au top electrodes. Fitting reflectivity spectra to Fresnel formulas yields extraordinary and ordinary refractive indices n(e) = 2.232 and n(o) = 2.234 as well as electro-optic coefficient r(13) = 17.4 pm/V. Dispersion of the refraction index follows the Sellmeier formula n(2) = 1 + 3.46/[1-(244 nm/lambda)(2)] in the range from 400 nm to 850 nm.
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| 44. |
- Khartsev, Sergiy, et al.
(författare)
-
Colossal magnetoresistance in ultrathin epitaxial La0.75Sr0.25MnO3 films
- 2000
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 87:5, s. 2394-2399
-
Tidskriftsartikel (refereegranskat)abstract
- We present results on magnetotransport measurements of a series of La0.75Sr0.25MnO3 films with thickness ranging from 32 to 3300 Angstrom. Films were fabricated using pulsed laser deposition onto SrTiO3 and LaAlO3 substrates. The substrate-film lattice mismatch causes strain in ultrathin films which diminishes with increasing thickness. Ultrathin films exhibit perfect match of in-plane film and substrate lattice parameters. The inhomogeneity of lattice parameters in thick films is caused by film-substrate mismatch strain and displayed by nonuniform broadening of x-ray diffraction Bragg reflections. The observation of characteristic Kiessig fringes is evidence for very uniform thickness of fabricated films. We found that the magnetotransport properties are strongly controlled by the film thickness and that allowed us to tailor the temperature of the metal-to-semiconductor phase transition in the range of 100-340 K with a change in magnetoresistivity within a factor of 3. We also present comparisons between the thickness dependence and oxygen deficiency in the films.
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| 45. |
- Khartsev, Sergiy, et al.
(författare)
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Comparative characteristics of Na0.5K0.5NbO 3 films on Pt by pulsed laser deposition and magnetron sputtering
- 2003
-
Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 55, s. 769-779
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Tidskriftsartikel (refereegranskat)abstract
- Ferroelectric Na0.5K0.5NbO3 (NKN) thin films were grown on the Pt80Ir20 polycrystalline substrates by pulsed laser deposition (PLD) and radio frequency-magnetron sputtering (RF) technique using the same stoichiometric Na0.5K 0.5NbO3 ceramic target. X-ray diffraction proved both PLD- and RF-made Na0.5K0.5NbOj/Pt80Ir20 films are single phase and have preferential c-axis orientation. Temperature dependence of dielectric permittivity reveals the presence of two phase transitions around 210 and 410°C. Capacitance vs. applied voltage C-V @ 100 kHz, I-V, and P-E hysteresis characteristics recorded for the vertical capacitive structures yielded loss tan δ = 0.026 and 0.016, tunability about 44.5 and 30% @ 100 kV/cm, Ohmic resistivity 6.7 × 1012 Ω·cm and 0.2 × 1012 Ω·cm, remnant polarization 11.7 and 9.7 μC/cm2, coercive field 28.0 and 94.6 kV/cm for PLD- and RF-films, respectively. Piezoelectric test carried out in hydrostatic conditions showed piezoelectric coefficient dH = 21 for PLD-NKN and 15 pC/N for RF-NKN film.
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| 46. |
- Khartsev, Sergiy, et al.
(författare)
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Heteroepitaxial Bi3Fe5O12/La3Ga5O12 films for magneto-optical photonic crystals
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:14
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial La3Ga5O12 (LGG) garnet films and Bi3Fe5O12/La3Ga5O12 (BIG/LGG) heteroepitaxial film structures have been synthesized on the Gd3Ga5O12(GGG,111) single crystal. LGG films were grown by pulsed laser deposition technique whereas rf-magnetron sputtering was used to grow BIG films. LGG has a lattice constant 12.768 A that is bigger than that in GGG (12.384 A) and closer to that in BIG (12.626 A). We demonstrate feasibility of integration lanthanum gallium garnet with a giant Faraday rotator Bi3Fe5O12 in magneto-optical photonic crystals. Heteroepitaxial Bi3Fe5O12(1.9 mu m)/La3Ga5O12(300 nm)/GGG(111) structures show Faraday rotation as high as 5.74 deg/mu m compared to 5.46 deg/mu m in BIG/GGG at lambda=655 nm. Fitting LGG reflectivity spectra to Fresnel formulas yields LGG refractive index n(o)=1.981 compared to 1.963 in GGG at 655 nm. Dispersion of LGG refraction index follows Sellmeier formula n(o)(2)=1+2.77/[1-(143 nm/lambda)(2)] in the range from 400 nm to 1000 nm.
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| 47. |
- Khartsev, Sergiy, et al.
(författare)
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Heteroepitaxial Na0.5K0.5NbO3/La0.5Sr0.5CoO3 electro-optical cell
- 2006
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Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 80, s. 133-143
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Tidskriftsartikel (refereegranskat)abstract
- We report electro-optic performance of heteroepitaxial Na0.5K0.5NbO3(1.5 mu m)/La0.5Sr0.5CoO3 (0.5 mu m) (NKN/LSCO) films grown on Al2O3(01 (1) under bar2) single crystal (r-cut sapphire) by rf-magnetron sputtering (NKN) and pulsed laser deposition (LSCO) techniques. Vertical capacitive electro-optical cells were defined by a thermal evaporation of 2 x 8 mm(2) Au electrodes through the contact mask on top the NKN film. Processing parameters have been specially optimized to obtain electrosoftNKN films with a non-linear fatigue-free P-E characteristics: low remnant P-r = 7.7 mu C/cm(2) high induced polarization P = 23 mu C/cm(2) @ 400 km/cm , and the coercive field E-c = 70 kV/cm. Electro-optical characterization of NKN films has been performed using waveguide refractometry: a prism coupling of a light beam into the thin-film waveguide modes. Intensity of TM- and TE-polarized light of 655 nm laser diode reflected from the free surface of NKN film and Au-clad NKN/LSCO waveguide was recorded at zero and 15 V (100 kV/cm) bias electric field. Fitting reflectivity spectra to Fresnel formulas yields extraordinary and ordinary refractive indices n(c) = 2.232 and n(o) = 2.234 as well as electro-optic coefficient r(13) = 17.4 pm/V. Dispersion of the refraction index follows Sellmeier formula n(2) = 1+ 3.46/[1 + (244 nm/lambda)(2)] in the range from 400 nm to 850 nm.
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| 48. |
- Khartsev, Sergiy, et al.
(författare)
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High performance Bi3Fe5O12/Sm3Ga5O12 (m) magneto-optical photonic crystals
- 2007
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 101:5
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Tidskriftsartikel (refereegranskat)abstract
- We report the properties of one-dimensional heteroepitaxial all-garnet magneto-optical (MO) photonic crystals (MOPCs) composed of alternating MO-active Bi3Fe5O12 (BIG) and transparent Sm3Ga5O12 (SGG) quarter-wavelength layers grown by rf-magnetron sputtering on Ca,Mg,Zr:Gd3Ga5O12(111) and Gd3Sc2Ga3O12(001) crystals. MOPCs' spectra, as designed, exhibit a stop band structure and a band gap with the transmittance central peak at 750 nm caused by light localization in the half-wavelength BIG cavity. A series of MOPCs with different numbers of [BIG/SSG](m) reflectors (m=4, 5, and 6) has been fabricated to optimize the specific Faraday rotation theta(F) (deg/mu m) and MO-quality factor Q(deg)=2 parallel to theta(F)parallel to/absorption coefficient. A close BIG-to-SGG lattice match enabled significant improvement of [Bi3Fe5O12/Sm3Ga5O12](m) properties compared to previously reported [Bi3Fe5O12/Y3Fe5O12](m) [S. Kahl and A. M. Grishin, Appl. Phys. Lett. 84, 1438 (2004)] and [Bi3Fe5O12/Gd3Ga5O12](m) [S. I. Khartsev and A. M. Grishin, Alexander M.
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| 49. |
- Khartsev, Sergiy, et al.
(författare)
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Integration of colossal magnetoresistors with GaAs
- 2005
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 284:02-jan, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- Colossal magnetoresistive (CMR) La0.67Ca0.33MnO3 (LCMO) and La0.67Sr0.33MnO3 (LSMO) films have been grown by pulsed laser deposition technique on GaAs(001) substrates buffered with epitaxial MgO layer. X-ray diffraction revealed strong c-axis out-of-plane orientation and strong in-plane texture of CMR/MgO bilayers on GaAs single crystal. The maximum temperature coefficient of resistivity TCR = 9.0% K-1 at 223 K and 2.0% K-1 at 327 K. and the magnetoresistance Delta rho/rho similar to-7.95% kOe(-1) and -1.47% kOe(-1) have been achieved for LCMO/MgO/GaAs and LSMO/MgO/GaAs heteroepitaxial structures, respectively. Comparison with the test LCMO and LSMO films grown directly onto the bulk MgO(001) single cry tal demonstrates the identity of LSMO/MgO/GaAs and LSMO/MgO films properties whereas the LCMO films grown on MgO buffered GaAs show lower transition temperature T-c = 242 K compared to 253 K in LCMO/MgO.
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| 50. |
- Khartsev, Sergiy, et al.
(författare)
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New garnet films for magneto-optical photonic crystals
- 2005
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Ingår i: Magneto-Optical Materials For Photonics and Recording. - WARRENDALE : MATERIALS RESEARCH SOCIETY. - 1558997822 ; , s. 47-52
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Konferensbidrag (refereegranskat)abstract
- Epitaxial La3Ga5O12 (LGG) garnet films and Bi3Fe5O12/La3Ga5O12 (BIG/LGG) heteroepitaxial structures have been synthesized on Gd3Ga5O12(GGG,111) single crystal. LGG films were grown by Pulsed Laser Deposition (PLD) technique whereas rf-magnetron sputtering was used to grow BIG films. We demonstrate LGG is a promising material to be integrated with a giant Faraday rotator Bi3Fe5O12 in magneto-optical photonic crystals. LGG has a lattice constant 12.772 angstrom that is bigger than that in GGG (12.384 angstrom) and closer to that in BIG (12.626 angstrom). Heteroepitaxial Bi3Fe5O12(2 mu m)/La3Ga5O12(300nm) structures grown on the GGG(111) single crystal show the Faraday rotation as high as 5.74 deg/mu m compared to 5.46 deg/mu m in BIG/GGG at lambda = 655 nm. Fitting LGG reflectivity spectra to Fresnel formulas yields LGG refractive index n = 1.981 compared to 1.963 in GGG at 655 nm. Dispersion of LGG refraction index follows Sellmeier formula n(2) = 1 + 2.78/[1 - (138nm/lambda)(2)] in the range from 400 nm to 1000 nm.
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