Temperature-dependent Raman scattering of multiferroic Pb(Fe(1/2)Nb(1/2))O₃

Raman scattering measurements on multiferroic Pb(Fe(1/2)Nb(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 approximately 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 BO(6) units revealed an anomalous frequency shift below T(N) approxiamtely 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(*).