A high resolution, hard x-ray photoemission investigation of La_(2-2x)Sr_(1+2x)Mn_2O_7 (0.30<x<0.50): on microscopic phase separation and the surface electronic structure of a bilayered CMR manganite

TL;DR

This study uses high-resolution hard x-ray photoemission to analyze the surface and bulk electronic structures of a bilayered manganite, revealing no microscopic phase separation above the Curie temperature.

Contribution

It demonstrates that the surface electronic structure matches the bulk in La_(2-2x)Sr_(1+2x)Mn_2O_7 and shows microscopic phase separation is unlikely at high temperatures.

Findings

Surface and bulk electronic structures are identical.

Microscopic phase separation is unlikely above the Curie temperature.

Hard x-ray photoemission effectively probes bulk properties.

Abstract

Photoemission data taken with hard x-ray radiation on cleaved single crystals of the bilayered, colossal magnetoresistant manganite La_(2-2x)Sr_(1+2x)Mn_2O_7 (LSMO) with 0.30<x<0.50 are presented. Making use of the increased bulk-sensitivity upon hard x-ray excitation it is shown that the core level footprint of the electronic structure of the LSMO cleavage surface is identical to that of the bulk. Furthermore, by comparing the core level shift of the different elements as a function of doping level x, it is shown that microscopic phase separation is unlikely to occur for this particular manganite well above the Curie temperature.