2001/08/23 by A. Malinowski, Marta Z. Cieplak, S. Guha +13
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #cond-mat
paper · pdf · doi:10.1103/physrevb.66.104512
arxiv created 2001/08/23 · openalex publication_date 2002/09/17 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We have studied the magnetotransport properties in the normal state for a series of La1.85Sr0.15Cu_1\ensuremath-yZnyO4 films with values of y between 0 and 0.12. A variable degree of compressive or tensile strain results from the lattice mismatch between the substrate and the film, and affects the transport properties differently from the influence of the zinc impurities. In particular, the orbital magnetoresistance (OMR) varies with y but is strain-independent. The relations for the resistivity (\ensuremathρ=\ensuremathρ0+AT) and the Hall angle (cot\ensuremathΘH=\ensuremathαT2+C), and the proportionality between the OMR and tan2\ensuremathΘH (\ensuremathΔ\ensuremathρ/\ensuremathρ=\ensuremathζtan2\ensuremathΘH) are followed above about 70 K. We have been able to separate the strain and impurity effects by rewriting the last two of these relations as cot\ensuremathΘH/\ensuremathα=T2+C/\ensuremathα and \ensuremathΔ\ensuremathρ/\ensuremathρ=(\ensuremathζ/\ensuremathα2)(\ensuremathα2tan2\ensuremathΘH), where each term is strain-independent and depends on y only. We also find that changes in the lattice constants give rise to approximately the same fractional changes in A, C, and \ensuremathα, while \ensuremathρ0 is, in addition, increased by changes in the microstructure. The OMR is more strongly suppressed by the addition of impurities than tan2\ensuremathΘH, so that \ensuremathζ decreases as y increases. We conclude that the relaxation rate that governs the Hall effect is not the same as for the magnetoresistance. We also suggest a correspondence between the transport properties and the opening of the pseudogap at a temperature which changes when the La-Sr ratio changes, but does not change with the addition of the zinc impurities. Several theoretical models seem to be in conflict with our results. Some recent ones may be more compatible, but have not been carried sufficiently far for a detailed comparison.