Optical Investigations of Charge Gap in Orbital Ordered La1/2Sr3/2MnO4

TL;DR

This study investigates the temperature and polarization dependence of the electronic structure in La1/2Sr3/2MnO4 using optical conductivity, revealing how orbital ordering and Jahn-Teller distortion influence the charge gap and spectral features.

Contribution

It provides new insights into the relationship between orbital ordering, Jahn-Teller distortion, and optical conductivity in La1/2Sr3/2MnO4, highlighting temperature-dependent spectral changes.

Findings

MIR peak narrows and shifts to higher frequency with decreasing temperature for E//ab

MIR peak in Nd1/2Sr3/2MnO4 remains nearly temperature independent

Jahn-Teller distortion significantly affects the MIR peak's width and position

Abstract

Temperature and polarization dependent electronic structure of La1/2Sr3/2MnO4 were investigated by optical conductivity analyses. With decreasing temperature, for E//ab, a broad mid-infrared (MIR) peak of La1/2Sr3/2MnO4 becomes narrower and moves to the higher frequency, while that of Nd1/2Sr3/2MnO4 nearly temperature independent. We showed that the MIR peak in La1/2Sr3/2MnO4 originates from orbital ordering associated with CE-type magnetic ordering and that the Jahn-Teller distortion has a significant influence on the width and the position of the MIR peak.