Giant Magneto-Resistance in Nd$_{0.7}$Sr$_{0.3}$MnO$_3$ at Optical Frequencies

TL;DR

This study investigates the optical properties of Nd$_{0.7}$Sr$_{0.3}$MnO$_3$ thin films across a broad energy range and temperature spectrum, revealing spectral weight transfer linked to magnetic and electronic interactions.

Contribution

It provides new insights into the optical behavior of Nd$_{0.7}$Sr$_{0.3}$MnO$_3$ and supports models involving double exchange and Jahn-Teller effects.

Findings

Spectral weight shifts from high to low energy below 180 K

Optical data align with double exchange and Jahn-Teller models

Temperature and magnetic field influence optical spectral distribution

Abstract

The optical properties of Nd$_{0.7}$Sr$_{0.3}$MnO$_3$ thin films have been studied from 5 meV to 25 meV and from 0.25 eV to 3 eV, at temperatures from 15 K to 300 K and magnetic fields up to 8.9 T. A large transfer of spectral weight from high energy to low energy occurs as the temperature is decreased below 180 K, where the dc resistivity peaks, or as the magnetic field is increased. The optical data are found to be consistent with models that include both the double exchange interaction and the dynamic Jahn-Teller effect on the Mn$^{3+}$ e$_g$ levels.