Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
J Phys Condens Matter. 2011 Jan 12;23(1):015401. doi: 10.1088/0953-8984/23/1/015401. Epub 2010 Dec 6.
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().
我们对多铁性 Pb(Fe(1/2)Nb(1/2))O₃在 10 至 500 K 的宽温度范围内进行了喇曼散射测量。我们观察到非常宽且重叠的峰（一级特征）和大约在 1130 cm(-1)处的突出高频峰，我们将其归因于双声子峰。这些特征在特征温度 T()∼330 K 处表现出拉曼散射强度和光谱形状的显著变化，清楚地显示了大约 T()处的结构晶格变化。BO(6)单元的一些伸缩振动模式的温度依赖性在低于大约 143 K 的 T(N)处显示出异常的频率位移。声子频率在 T(N)处的这些异常偏差与自旋-声子耦合机制有关。补充的磁数据证实了室温下的弱磁有序，并且有趣的是在大约 T()处显示出异常。这些结果表明，在 PFN 中，铁电、结构和磁自由度之间存在相互作用，这种相互作用在大约 T()处开始变得显著。
