Temperature-Dependent Raman Scattering of Multiferroic Pb(Fe1/2Nb1/2)O3
Raman scattering measurements on multiferroic Pb(Fe1/2Nb1/2)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 TN ~ 143 K. These anomalous deviations at TN 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*.
García-Flores, A. F.; Tenne, Dmitri A.; Choi, Y. J.; Ren, W. J.; Xi, X. X.; and Cheong, S. W.. (2011). "Temperature-Dependent Raman Scattering of Multiferroic Pb(Fe1/2Nb1/2)O3". Journal of Physics: Condensed Matter, 23(1), 015401-1 - 015401-6. http://dx.doi.org/10.1088/0953-8984/23/1/015401