Electronic and vibrational Raman spectroscopy of Nd$_{0.5}$Sr$_{0.5}$MnO$_3$ through the phase transitions

TL;DR

This study uses Raman spectroscopy to investigate electronic and vibrational changes in Nd$_{0.5}$Sr$_{0.5}$MnO$_3$ across phase transitions, revealing persistent electronic responses and phonon modifications.

Contribution

It provides detailed insights into the electronic and vibrational behavior of Nd$_{0.5}$Sr$_{0.5}$MnO$_3$ during phase transitions, highlighting coexistence of phases and phonon anomalies.

Findings

Diffusive electronic Raman response persists in the ferromagnetic phase.

Phonon frequency and linewidth change significantly across transitions.

Electronic response disappears below 150 K, indicating phase coexistence.

Abstract

Raman scattering experiments have been carried out on single crystals of Nd$_{0.5}$Sr$_{0.5}$MnO$_3$ as a function of temperature in the range of 320-50 K, covering the paramagnetic insulator-ferromagnetc metal transition at 250 K and the charge-ordering antiferromagnetic transition at 150 K. The diffusive electronic Raman scattering response is seen in the paramagnetic phase which continue to exist even in the ferromagnetic phase, eventually disappearing below 150 K. We understand the existence of diffusive response in the ferromagnetic phase to the coexistence of the different electronic phases. The frequency and linewidth of the phonons across the transitions show significant changes, which cannot be accounted for only by anharmonic interactions.