Spin polarized tunneling in the half-metallic ferromagnet La0.7Sr0.3MnO3: experiment and theory

TL;DR

This paper combines experimental measurements and theoretical modeling to analyze spin polarized tunneling effects on magnetoresistance in polycrystalline La0.7Sr0.3MnO3, revealing good agreement between theory and experiment.

Contribution

It introduces a theoretical expression for spin polarized tunneling contribution to magnetoresistance in granular ferromagnetic systems and validates it with experimental data.

Findings

Theoretical model matches experimental MR dependence on magnetization.

Spin polarized tunneling significantly influences MR in polycrystalline La0.7Sr0.3MnO3.

Good agreement between theory and experiment supports the model's validity.

Abstract

The magnetoresistance (MR) in polycrystalline colossal magnetoresistive compounds follows a behavior different from single crystals below the ferromagnetic transition temperature. This difference is usually attributed to spin polarized tunneling at the grain boundaries of the polycrystalline sample. Here we derive a theoretical expression for the contribution of spin polarized tunneling to the magnetoresistance in granular ferromagnetic systems under the mean field approximation. We apply this model to our experimental data on the half metallic ferromagnet La0.7Sr0.3MnO3, and find that the theoretical predictions agree quite well with the observed dependence of the spin polarized MR on the spontaneous magnetization.