| 1. |
- Ovsyannikov, Gennady, 1948, et al.
(författare)
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Conductivity and antiferromagnetism of CaCuO2 thin films doped by Sr
- 2007
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Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 460-462:Part 1, 1 September 2007, s. 536-537
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Tidskriftsartikel (refereegranskat)abstract
- The results of electrical and magnetic investigations of epitaxial CaxSr1-xCuO2 (CSCO) thin films grown by pulsed laser deposition are presented. The experimental temperature dependence of the CSCO film conductivity at low doping level is well described by the 3-d Mott insulator model over a wide temperature range (4.2-300 K). A deviation from the model with changing of Sr concentration has been observed. The Neel temperature of the films, T-N, was determined by electron paramagnetic resonance technique. The comparison of the obtained TN value with the one previously obtained for the CSCO powder sample could be caused by oxygen vacancies in the CSCO films. Nb/Au/Ca1-xSrxCuO2/YBa2Cu3O7-delta heterostructures have been fabricated and superconducting current has been observed at low temperatures. (c) 2007 Elsevier B.V. All rights reserved.
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| 2. |
- Ovsyannikov, Gennady, 1948, et al.
(författare)
-
Magnetotransport characteristics of strained La0.7Sr0.3MnO3 epitaxial manganite films
- 2009
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Ingår i: Journal of Experimental and Theoretical Physics. - 1090-6509 .- 1063-7761. ; 108:1, s. 48-55
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Tidskriftsartikel (refereegranskat)abstract
- The electrical and magnetic characteristics of La0.7Sr0.3MnO3 (LSMO) epitaxial manganite films are investigated by different methods under conditions when the crystal structure is strongly strained as a result of mismatch between the lattice parameters of the LSMO crystal and the substrate. Substrates with lattice parameters larger and smaller than the nominal lattice parameter of the LSMO crystal are used in experiments. It is shown that the behavior of the temperature dependence of the electrical resistance for the films in the low-temperature range does not depend on the strain of the film and agrees well with the results obtained from the calculations with allowance made for the interaction of electrons with magnetic excitations in the framework of the double-exchange model for systems with strongly correlated electronic states. Investigations of the magneto- optical Kerr effect have revealed that an insignificant (0.3%) orthorhombic distortion of the cubic lattice in the plane of the NdGaO3(110) substrate leads to uniaxial anisotropy of the magnetization of the film, with the easy-magnetization axis lying in the substrate plane. However, LSMO films on substrates (((LaAlO3)(0.3)+(Sr2AlTaO6)(0.7))(001)) ensuring minimum strain of the films exhibit a biaxial anisotropy typical of cubic crystals. The study of the ferromagnetic resonance lines at a frequency of 9.76 GHz confirms the results of magnetooptical investigations and indicates that the ferromagnetic phase in the LSMO films is weakly inhomogeneous.
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