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Grain boundary effects on magnetotransport in bi-epitaxial films of La$_{0.7}$Sr$_{0.3}$MnO$_3$

R. Mathieu·P. Svedlindh·R. A. Chakalov·Z. G. Ivanov
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Abstract

The low field magnetotransport of La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) films grown on SrTiO$_3$ substrates has been investigated. A high qualtity LSMO film exhibits anisotropic magnetoresistance (AMR) and a peak in the magnetoresistance close to the Curie temperature of LSMO. Bi-epitaxial films prepared using a seed layer of MgO and a buffer layer of CeO$_2$ display a resistance dominated by grain boundaries. One film was prepared with seed and buffer layers intact, while a second sample was prepared as a 2D square array of grain boundaries. These films exhibit i) a low temperature tail in the low field magnetoresistance; ii) a magnetoconductance with a constant high field slope; and iii) a comparably large AMR effect. A model based on a two-step tunneling process, including spin-flip tunneling, is discussed and shown to be consistent with the experimental findings of the bi-epitaxial films.

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R. Mathieu, P. Svedlindh, R. A. Chakalov, Z. G. Ivanov. 2000-07-11. Grain boundary effects on magnetotransport in bi-epitaxial films of La$_{0.7}$Sr$_{0.3}$MnO$_3$. https://doi.org/10.1103/physrevb.62.3333

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