Temperature-Dependent Raman Scattering of Multiferroic Pb(Fe_1/2Nb_1/2)O₃

A. F. García-Flores, Pennsylvania State University
Dmitri A. Tenne, Boise State University
Y. J. Choi, Rutgers University
W. J. Ren, Chinese Academy of Sciences
X. X. Xi, Pennsylvania State University
S. W. Cheong, Rutgers University

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Journal of Physics-Condensed Matter, Volume 23, Issue 1, 015401-1 - 015401-6. DOI: 10.1088/0953-8984/23/1/015401

Abstract

Raman scattering measurements on multiferroic Pb(Fe_1/2Nb_1/2)O₃ over a wide temperature range from 10 to 500 K were performed. Very broad and overlapping peaks (first-order character) and a prominent high-frequency peak at ~ 1130 cm ^{− 1}, which we assign as a two-phonon peak, were observed. These features showed remarkable changes in their Raman scattering intensity and spectral shape at the characteristic temperature T^* ~ 330 K, clearly showing a structural lattice change at around T^*. The temperature dependence of some stretching vibration modes of the BO₆ units revealed an anomalous frequency shift below T_N ~ 143 K. These anomalous deviations at T_N of the phonon frequency are associated with the spin–phonon coupling mechanism. Complementary magnetic data confirmed a weak magnetic ordering at room temperature and interestingly showed an anomaly at about T^*. These results suggest an interplay between ferroelectric, structural and magnetic degrees of freedom in PFN, starting to be significant at around T^*.