Spin-phonon coupling in multiferroic RCrO3 (R-Y, Lu, Gd, Eu, Sm): A Raman study

Raman study on a select few orthochromites, RCrO3 (R = Y, Lu, Gd, Eu and Sm), shows that the phonon behavior at T-N in compounds with magnetic R-ion (Gd and Sm) is remarkably different from that of non-magnetic R-ion (Y, Lu and Eu). While anomalies in most of the observed phonon frequencies in all these compounds may result from the distortion of CrO6 octahedra due to size effect and magnetostriction arising from Cr-ordering, the anomalous behavior of their linewidths observed at T-N for the compounds with only magnetic R-ion suggests spin-phonon coupling. The presence of spin-phonon coupling and the anomalies in the low-frequency modes related to R-ion motion in orthochromites (R = Gd and Sm) support the suggestion that the coupling between 4f-3d moments play an important role in inducing switchable electric polarization. Copyright (C) EPLA, 2013