Laser microscopy of tunneling magnetoresistance in manganite grain-boundary junctions

TL;DR

This study employs low-temperature scanning laser microscopy to visualize and analyze the local electric transport and magnetic domain behavior in manganite grain-boundary junctions, revealing resistive state switching and domain wall dynamics.

Contribution

It introduces direct imaging of electric transport and magnetic domain evolution in manganite grain boundaries, providing new insights into their resistive switching mechanisms.

Findings

Grain boundary switches between resistive states due to magnetic domain formation.

Domain walls nucleate at edges and grow across the grain boundary.

Local resistance varies with temperature and magnetic domain configuration.

Abstract

Using low-temperature scanning laser microscopy we directly image electric transport in a magnetoresistive element, a manganite thin film intersected by a grain boundary (GB). Imaging at variable temperature allows reconstruction and comparison of the local resistance vs temperature for both, the manganite film and the GB. Imaging at low temperature also shows that the GB switches between different resistive states due to the formation and growth of magnetic domains along the GB. We observe different types of domain wall growth; in most cases a domain wall nucleates at one edge of the bridge and then proceeds towards the other edge.