High Temperature Neutron Diffraction Study of the La1.4Sr1.6mn2o7 Bilayered Manganite

TL;DR

This study investigates high-temperature structural changes in La1.4Sr1.6Mn2O7 bilayered manganite using neutron diffraction, revealing unusual bond parameter trends and suggesting electronic density shifts with temperature.

Contribution

It provides new insights into the temperature-dependent structural and electronic behavior of bilayered manganites through neutron diffraction analysis.

Findings

Unusual <Mn-Oapical>/Mn-Oequatorial trend with temperature

Significant shortening of apical Mn-O(2) bond near 500 K

Evidence of short-range magnetic interactions above TC

Abstract

In this paper we present the results of a high temperature (300 K<T<800 K) neutron powder diffraction study of the La1.4Sr1.6Mn2O7 bilayered manganite. An unusual trend of the <Mn-Oapical>/Mn-Oequatorial parameter was found: it first decreases up to 500 K and then increases up to the highest T measured. At the same time, a significant shortening of the apical Mn-O(2) bond is observed in the range where the J-T distortion is reduced. The overall data gained by this study may suggest a shift of electronic density from axial to planar eg orbitals with T. This trend is explained considering of the presence of short range magnetic interaction well above TC.