Spin-phonon coupling in multiferroic RCrO3 (R-Y, Lu, Gd, Eu, Sm): A Raman study
Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research Jakkur P. O., Bangalore 560 064, India
Received: 6 October 2012
Accepted: 13 December 2012
Raman study on a select few orthochromites, RCrO3 (R = Y, Lu, Gd, Eu and Sm), shows that the phonon behavior at TN 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 TN 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.
PACS: 78.30.-j – Infrared and Raman spectra / 75.85.+t – Magnetoelectric effects, multiferroics / 75.47.Lx – Magnetic oxides
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