| 1. |
- Kalaboukhov, Alexei, 1975, et al.
(författare)
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Electrical and structural properties of ABO3/SrTiO3 interfaces
- 2012
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Ingår i: Materials Research Society Symposium Proceedings. - Warrendale, Pa. : Springer Science and Business Media LLC. - 0272-9172. - 9781605114316 ; 1454, s. 167-172, s. 167-172
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Konferensbidrag (refereegranskat)abstract
- Electrical transport and microstructure of interfaces between nm-thick films of various perovskite oxides grown by pulsed laser deposition (PLD) on TiO2 terminated SrTiO3 (STO) substrates are compared. LaAlO3/STO and KTaO3/STO interfaces become quasi-2DEG after a critical film thickness of 4 unit cell layers. The conductivity survives long anneals in oxygen atmosphere. LaMnO3/STO interfaces remain insulating for all film thicknesses and NdGaO3/STO interfaces are conducting but the conductivity is eliminated after oxygen annealing. Medium-energy ion spectroscopy and scanning transmission electron microscopy detect cationic intermixing within several atomic layers from the interface in all studied interfaces. Our results indicate that the electrical reconstruction in the polar oxide interfaces is a complex combination of different mechanisms, and oxygen vacancies play an important role.
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| 2. |
- Boikov, Yu A., et al.
(författare)
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Effect of interfaces on the dielectric response of a SrTi O3 layer between metallic oxide electrodes
- 2006
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 74:2
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Tidskriftsartikel (refereegranskat)abstract
- The temperature dependence of the dielectric permittivity ε of an 800 nm thick SrTi O3 layer in epitaxial SrRu O3 SrTi O3 SrRu O3 and Y Ba2 Cu3 O7-δ SrTi O3 SrRu O3 heterostructures followed the relation ε-1 = ε0 -1 C0 -1 (T- TCW) + εI -1, where C0 and TCW are the Curie constant and the Curie-Weiss temperature for the strontium titanate bulk crystal, respectively. The effective dielectric constant is lower than the bulk value due to the interfaces of the SrTi O3 film to its electrodes as given by εI. The εI was diminished roughly 2.5 times when the top SrRu O3 electrode in the trilayer was replaced by one of Y Ba2 Cu3 O7-δ. The capacitances Ci per unit area of the SrRu O3 SrTi O3 and Y Ba2 Cu3 O7-δ SrTi O3 interfaces were 8.2 and 2.3 F cm2, respectively. Characteristic penetration depths L of the electric field into the SrRu O3 and Y Ba2 Cu3 O7-δ electrodes were extracted from the Ci s and are several times larger than corresponding data estimated from free electron type models of metals. A diminished charge carrier density in the electrode very close to the interface is a likely reason for the enhanced L. © 2006 The American Physical Society.
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| 3. |
- Boikov, Yu A., et al.
(författare)
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Structure and magneto-transport parameters of partially relaxed and coherently grown La0.67Ba0.33MnO3 films
- 2013
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Ingår i: Physics of the Solid State. - 1063-7834 .- 1090-6460. ; 55:10, s. 2043-2050
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Tidskriftsartikel (refereegranskat)abstract
- X-ray diffraction (XRD) and medium-energy ion scattering (MEIS) have been used to reveal distortions in the crystal lattice of La0.67Ba0.33MnO3 (LBMO) films formed in relaxation of mechanical stresses. The LBMO films 25 nm thick have been prepared by laser deposition. The XRD and MEIS data obtained suggest that biaxially and mechanically elastically stressed LBMO layers grow coherently on LSATO substrates, whose crystal lattice parameter differs only weakly from the corresponding LBMO parameter, whereas in the bulk of manganite films grown on LaAlO3 substrates, stresses relax partially. Stresses do not relax in the LBMO interface about 4 nm thick adjoining LaAlO3. The electro- and magneto-transport parameters of partially relaxed LBMO films have been compared with those obtained for coherently grown manganite films with approximately the same tetragonal distortion of the lattice cell (a (aSyen)/a (aEuro-) = 1.024-1.030; a (aEuro-) and a (aSyen) are the unit cell parameters in the substrate plane and normal to it, respectively). At temperatures substantially lower than the Curie temperature, the electrical resistivity rho of LBMO films fits the relation rho = rho(0) + rho(1) T (2) + rho(2)(H)T (4.5); the coefficients rho(0) and rho(1) do not depend on temperature T and magnetic field, and rho(2) does not depend on temperature but almost linearly decreases with increasing magnetic field strength H. The coefficient rho(2) for partially relaxed LBMO films is substantially larger than that for coherently grown manganite layers.
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| 4. |
- Kalaboukhov, Alexei, 1975, et al.
(författare)
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Inhomogeneous Microstructure and Electrical Transport Properties at the LaAlO3/SrTiO3 Interface
- 2012
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Ingår i: Japanese Journal of Applied Physics. - 1347-4065 .- 0021-4922. ; 51:11(spec.issue), s. article no. 11PG10 -
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Tidskriftsartikel (refereegranskat)abstract
- Medium-energy ion spectroscopy (MEIS), scanning transmission electron microscopy (STEM) and X-ray photoemission spectroscopy (XPS) were used to investigate the composition and microstructure of LaAlO3/SrTiO3 (LAO/STO) interfaces grown by pulsed laser deposition of LAO on TiO2-terminated STO substrates under different oxidizing conditions. MEIS and XPS indicated Sr/La and Al/Ti intermixing within several atomic layers at all studied interfaces. XPS and STEM revealed that La diffuses deeper than Al. Analysis of the MEIS data suggests inhomogeneous lateral distribution of the diffused elements. This is further supported by the observation of a large positive magneto-resistance at low temperatures. We discuss the role of lateral inhomogeneities on the formation of the electron gas at the LAO/STO interface.
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