Electrical resistivity anomaly, valence shift of Pr ion, and magnetic behavior in epitaxial (Pr.sub.1-y./sub.Y.sub.y./sub.).sub.1-x./sub.Ca.sub.x./sub.CoO.sub.3./sub. thin films under compressive strain

0485352 - FZÚ 2018 RIV US eng J - Journal Article
Fujishiro, H. - Noda, Y. - Akuzawa, K. - Naito, T. - Ito, A. - Goto, T. - Maryško, Miroslav - Jirák, Zdeněk - Hejtmánek, Jiří - Nitta, K.
Electrical resistivity anomaly, valence shift of Pr ion, and magnetic behavior in epitaxial (Pr_1-yY_y)_1-xCa_xCoO₃ thin films under compressive strain.
Journal of Applied Physics. Roč. 121, č. 11 (2017), s. 1-8, č. článku 115104. ISSN 0021-8979. E-ISSN 1089-7550
R&D Projects: GA ČR GA17-04412S
Institutional support: RVO:68378271
Keywords : perovskite cobaltites * spin state transition * variable valence * epitaxial strain * XANES
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 2.176, year: 2017

We have fabricated (Pr1-yYy)1-xCaxCoO3 (PYCCO) epitaxial films with various thicknesses by pulsed laser deposition on the SrLaAlO4 (SLAO) substrate that applied an in-plane compressive stress to the film, and investigated the temperature dependence of the electrical resistivity, ρ(T), of the films. An anomalous ρ(T) upturn with a broad hysteresis could be clearly observed only for the thinnest film (d = 50 nm), and the ρ(T) anomaly decreased by increasing film thickness, d. The temperature dependence of the X-ray absorption near-edge structure (XANES) spectra at Pr L2-edge was measured for the films, and the valence states of praseodymium (Pr) ion were determined using the analysis of the XANES spectra. As a result, the average valence of the Pr ion in the d = 50 nm film slightly increases with decreasing temperature from the common value of 3.0+ around room temperature to 3.15+ at 8 K.
Permanent Link: http://hdl.handle.net/11104/0280780