Brillouin Scattering Studies of La_{0.77}Ca_{0.23}MnO_3 Across Metal-Insulator Transition

TL;DR

This study uses temperature-dependent Brillouin scattering to investigate elastic properties of La_{0.77}Ca_{0.23}MnO_3 across its metal-insulator transition, revealing shifts in acoustic wave frequencies and a peak at the transition temperature.

Contribution

It provides new insights into elastic constant variations and surface acoustic wave behavior across the metal-insulator transition in this manganite compound.

Findings

Blue-shifts in SRW and HVPSAW frequencies below T_C

Decrease in bulk acoustic wave frequencies below T_C

Maximum central peak width at T_C

Abstract

Temperature-dependent Brillouin scattering studies have been carried out on La_{0.77}Ca_{0.23}MnO_3 across the paramagnetic insulator - ferromagnetic metal (I-M) transition. The spectra show a surface Rayleigh wave (SRW) and a high velocity pseudo surface acoustic wave (HVPSAW) besides bulk acoustic waves (BAW). The Brillouin shifts associated with SRW and HVPSAW show blue-shifts, where as the frequencies of the BAW decrease below the I-M transition temperature (T_C) of 230 K. These results can be understood based on the temperature dependence of the elastic constants. We also observe a central peak whose width is maximum at T_C.