| 1. |
- Abrashev, M. V., et al.
(författare)
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Raman spectroscopy of CaMnO(3) : Mode assignment and relationship between Raman line intensities and structural distortions
- 2002
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 65:18, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Polarized Raman spectra of oriented finely twinned CaMnO(3) thin films and nonpolarized Raman spectra of CaMnO(3) ceramics were studied at room temperature using several excitation laser wavelengths. The selection rules for the polarized Raman spectra, obtained from samples consisting of finely twinned orthorhombic domains, were calculated and the symmetry of all observed Raman lines was determined. The relationship between the intensity of the Raman lines and the distortions in the ABO(3) perovskites with GdFeO(3)-type structure is discussed. These distortions can be described as superposition of four simple basic distortions: two MnO(6) octahedral tilts, Jahn-Teller deformation of Mn(3+) O(6) octahedra, and shift of the A ions from their sites in the ideal perovskite. Twenty of the 24 Raman-allowed modes in the real GdFeO(3)-type structure have counterparts in only one of the four simpler structures, obtained by a single basic distortion. The assignment of the Raman lines of CaMnO(3) to definite atomic vibrations, most of them activated by a single basic distortion, was made in close comparison with the results of lattice dynamical calculations and the Raman spectra of isostructural LaMnO(3) and CaGeO(3).
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| 2. |
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| 3. |
- Chakalov, R, et al.
(författare)
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Fabrication and investigation of YBa2Cu3O7-delta/Ba0.05Sr0.95TiO3 thin film structures for voltage tunable devices
- 1998
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Ingår i: Physica C: Superconductivity and its Applications. - 0921-4534. ; 308:3-4, s. 279-288
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature superconducting/ferroelectric thin film structures were deposited by laser ablation. Three types of voltage tunable devices were fabricated and investigated-trilayer capacitor, planar interdigital capacitor and coplanar waveguide. As ferroelectric the solid solution BaxSr1-xTiO3 was chosen with barium content x = 0.05 because its Curie temperature is close to the liquid nitrogen boiling point (77 K). Temperature and voltage dependences of the Ba0.05Sr0.95TiO3 dielectric constant epsilon(r,BSTO) were studied. High epsilon(r,BSTO) values were determined-up to 3000 at 75 K, 20 GHz and zero de bias. Efficient voltage tunability was demonstrated (up to 40%) at loss level tan delta=0.01-0.1. Compact YBa2Cu3O7-delta/Ba0.05Sr0.95TiO3 coplanar waveguide with as narrow gap as 18 mu m was tested as electrically tunable phase-shifter and field-induced phase shifts of more than 180 degrees were obtained by 35 V de bias at 20 GHz. This improvement was attained by proper choice of the ferroelectric material, accomplished epitaxial growth of the films and decrease of the specific dimensions. (C) 1998 Published by Elsevier Science B.V. All rights reserved.
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| 4. |
- Kahl, S., et al.
(författare)
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Structure, microstructure, and magneto-optical properties of laser deposited Bi3Fe5O12/Gd3Ga5O12(111) films
- 2002
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 91:12, s. 9556-9560
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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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| 5. |
- Kawano, K., et al.
(författare)
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BIG films fabricated by PLD for magnetic flux visualisation of YBCO
- 2002
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 372, s. 696-699
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Tidskriftsartikel (refereegranskat)abstract
- Bi3Fe5O12 (BIG) magneto-optic (MO) films have been grown onto (111) and (100) gadolinium gallium garnet substrates by pulsed laser deposition (PLD). X-ray and transmission electron microscopy measurements have confirmed the epitaxial growth of the BIG films oil both substrate orientations, Faraday rotation angles of both films showed linear field dependence from - 1600 to + 1600 G and the saturated Faraday rotation angle values were similar to5 deg/ pm and similar to7.8 deg/mum for the (111) and (100) oriented films, respectively. A change in the MO contrast of both films in applied magnetic field has been observed and magnetic nux distributions have been visualised in YBa2Cu3O- , (YBCO) bulk superconductor using the (001) oriented BIG film.
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| 6. |
- Mathieu, R, et al.
(författare)
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Grain-boundary effects on magnetotransport in La0.7Sr0.3MnO3 biepitaxial films
- 2000
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Ingår i: PHYSICAL REVIEW B. - : AMERICAN PHYSICAL SOC. - 0163-1829. ; 62:5, s. 3333-3339
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Tidskriftsartikel (refereegranskat)abstract
- The low field magnetotransport of La0.7Sr0.3MnO3 (LSMO) films grown pn SrTiO3 substrates has been investigated. A high quality LSMO film exhibits anisotropic magnetoresistance (AMR) and a peak in the magnetoresistance close to the Curie temperature of LSM
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| 7. |
- Mathieu, R, et al.
(författare)
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Magnetotransport in a bi-crystal film of La0.7Sr0.3MnO3
- 2001
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Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 226, s. 786-787
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Tidskriftsartikel (refereegranskat)abstract
- Transport properties of an epitaxial film of La0.7Sr0.3MnO3 (LSMO), deposited epitaxially on a LaAlO3 bi-crystal substrate having a misorientation angle of 9.2 degrees, have been studied. The film was patterned into a meander containing 100 grain boundari
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