声子
正交晶系
拉曼光谱
物理
谱线
结晶学
凝聚态物理
化学
晶体结构
光学
量子力学
作者
Mads C. Weber,Maël Guennou,Hong Jian Zhao,Jorge Íñiguez,R. Vilarinho,A. Almeida,J. Agostinho Moreira,J. Kreisel
出处
期刊:Physical review
日期:2016-12-07
卷期号:94 (21)
被引量:194
标识
DOI:10.1103/physrevb.94.214103
摘要
We report a Raman scattering study of six rare earth orthoferrites RFeO3, with R = La, Sm, Eu, Gd, Tb, Dy. The use of extensive polarized Raman scattering of SmFeO3 and first-principles calculations enable the assignment of the observed phonon modes to vibrational symmetries and atomic displacements. The assignment of the spectra and their comparison throughout the whole series allows correlating the phonon modes with the orthorhombic structural distortions of RFeO3 perovskites. In particular, the positions of two specific Ag modes scale linearly with the two FeO6 octahedra tilt angles, allowing the distortion throughout the series. At variance with literature, we find that the two octahedra tilt angles scale differently with the vibration frequencies of their respective Ag modes. This behavior as well as the general relations between the tilt angles, the frequencies of the associated modes and the ionic radii are rationalized in a simple Landau model. The reported Raman spectra and associated phonon-mode assignment provide reference data for structural investigations of the whole series of orthoferrites.
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