Dominant role of charge ordering on high harmonic generation in Pr_{0.6}Ca_{0.4}MnO_{3}

TL;DR

This study explores how charge ordering influences high harmonic generation in Pr_{0.6}Ca_{0.4}MnO_{3}, revealing that HHG intensity is affected by charge order transitions and can serve as a probe for local order fluctuations in correlated materials.

Contribution

It demonstrates the dominant role of charge ordering in modulating HHG in Pr_{0.6}Ca_{0.4}MnO_{3} and highlights HHG's potential as a tool to study electronic order fluctuations.

Findings

HHG intensity remains constant in the charge-disordered phase.

HHG intensity increases near the charge ordering transition.

HHG suppression at high temperatures is due to interference among CO configurations.

Abstract

High-harmonic generation (HHG) is a typical high-order nonlinear optical phenomenon and can be used to probe electronic structures of solids. Here, we investigate the temperature dependence of HHG from Pr_{0.6}Ca_{0.4}MnO_{3} in the range of 7 K to 294 K including the charge ordering (CO) transition and magnetic transition temperatures. The high-harmonic intensity remains almost constant in the high-temperature charge-disordered phase. However, as the temperature is lowered, it starts to gradually increase near the CO transition temperature where an optical gap related to the CO phase appears. The anomalous gap energy dependence resembles the one recently reported in a Mott insulator. We attribute the HHG suppression at high temperatures to the destructive interference among high-harmonic emissions from thermally activated multiple CO configurations. Our results suggest that HHG is a promising tool for probing the fluctuation of local order in strongly correlated systems.