Current dependence of grain boundary magnetoresistance in La_0.67Ca_0.33MnO_3 films

TL;DR

This study investigates how the magnetoresistance in La_0.67Ca_0.33MnO_3 films depends on current, revealing non-ohmic behavior and current-induced suppression of magnetoresistance, with implications for magnetic transport models.

Contribution

It introduces an explicit current dependence of spin polarization in grain boundary regions, advancing understanding of magnetic transport in manganite films.

Findings

Resistivity changes up to 70% due to magnetic domain switching.

High bias currents suppress magnetoresistance effect.

Current dependence aligns with tunneling and mesoscale magnetic transport models.

Abstract

We prepared epitaxial ferromagnetic manganite films on bicrystal substrates by pulsed laser ablation. Their low- and high-field magnetoresistance (MR) was measured as a function of magnetic field, temperature and current. At low temperatures hysteretic changes in resistivity up to 70% due to switching of magnetic domains at the coercitive field are observed. The strongly non-ohmic behavior of the current-voltage leads to a complete suppression of the MR effect at high bias currents with the identical current dependence at low and high magnetic fields. We discuss the data in view of tunneling and mesoscale magnetic transport models and propose an explicit dependence of the spin polarization on the applied current in the grain boundary region.