Direct observation of electronic domains in manganites by spatially resolved spectroscopy

TL;DR

This study employs spatially resolved spectroscopy to directly observe and characterize large insulating electronic domains within manganite crystals, revealing their size, behavior, and potential strain-related origins.

Contribution

It provides the first direct spectroscopic evidence of large insulating domains in manganites and links their formation to strain effects rather than chemical inhomogeneity.

Findings

Insulating domains are at least ten times larger than previously estimated.

Domains exhibit memory effects upon temperature cycling.

Domains are formed without chemical inhomogeneity, suggesting strain as a key factor.

Abstract

We use a spatially resolved, direct spectroscopic probe for electronic structure with an additional sensitivity to chemical compositions to investigate high-quality single crystal samples of La_{1/4}Pr_{3/8}Ca_{3/8}MnO_{3}, establishing the formation of distinct insulating domains embedded in the metallic host at low temperatures. These domains are found to be at least an order of magnitude larger in size compared to previous estimates and exhibit memory effects on temperature cycling in the absence of any perceptible chemical inhomogeneity, suggesting long-range strains as the probable origin.