Microwave imaging of mesoscopic percolating network in a manganite thin film

TL;DR

This study uses microwave impedance microscopy to visualize a mesoscopic, orientation-ordered percolating network in strained manganite thin films, revealing the role of elastic strain in phase separation and its connection to magnetoresistance.

Contribution

First observation of an orientation-ordered percolating network in strained manganite thin films using microwave impedance microscopy, highlighting anisotropic elastic strain effects.

Findings

Filamentary metallic domains align along specific crystal axes.

The network exhibits hysteretic electrical behavior.

Elastic strain influences phase separation and magnetoresistance.

Abstract

Many unusual behaviors in complex oxides are deeply associated with the spontaneous emergence of microscopic phase separation. Depending on the underlying mechanism, the competing phases can form ordered or random patterns at vastly different length scales. Using a microwave impedance microscope, we observed an orientation-ordered percolating network in strained Nd0.5Sr0.5MnO3 thin films with a large period of 100 nm. The filamentary metallic domains align preferentially along certain crystal axes of the substrate, suggesting the anisotropic elastic strain as the key interaction in this system. The local impedance maps provide microscopic electrical information of the hysteretic behavior in strained thin film manganites, suggesting close connection between the glassy order and the colossal magnetoresistance effects at low temperatures.