Local Tunneling Magnetoresistance probed by Low-Temperature Scanning Laser Microscopy

TL;DR

This study uses low-temperature scanning laser microscopy to investigate local magnetization configurations in a manganite junction, revealing domain behaviors and correlating local magnetization with tunneling magnetoresistance states.

Contribution

It introduces a method to directly visualize local magnetization in TMR devices and correlates local magnetic states with electrical resistance.

Findings

High-resistance state shows almost single-domain antiparallel magnetization.

Low-resistance state exhibits multidomain magnetization.

Calculated resistance from local magnetization matches measured magnetotransport data.

Abstract

Tunneling magnetoresistance (TMR) in a vertical manganite junction was investigated by low-temperature scanning laser microscopy (LTSLM) allowing to determine the local relative magnetization M orientation of the two electrodes as a function of magnitude and orientation of the external magnetic field H. Sweeping the field amplitude at fixed orientation revealed magnetic domain nucleation and propagation in the junction electrodes. For the high-resistance state an almost single-domain antiparallel magnetization configuration was achieved, while in the low-resistance state the junction remained in a multidomain state. Calculated resistance $R_\mathrm{calc}(H)$ based on the local M configuration obtained by LTSLM is in quantitative agreement with R(H) measured by magnetotransport.