Raman Scattering in charge ordered Pr_{0.63}Ca_{0.37}MnO_{3} : Anomalous Temperature Dependence of Linewidth

Abstract

We report the evolution of the Raman active A_g phonon modes in the charge-ordered manganite Pr_{0.63}Ca_{0.37}MnO_{3} as a function of temperature from 300K to 25K. Our studies reveal that the linewidths of A_g(2) and A_g(4) phonons increase as temperature decreases. This anomalous temperature dependence of phonon lineshapes, seen for the first time in charge ordered manganites, can be quantitatively understood in terms of strong spin-phonon coupling involving t_{2g} spins and A_g phonons.