铁电性
拉曼光谱
材料科学
分析化学(期刊)
结晶学
化学
物理
光学
色谱法
光电子学
电介质
作者
Xingliang Xu,Dong Meng,Xu–Guang Zheng,Qi Guo
标识
DOI:10.1088/1361-648x/abfe22
摘要
Abstract We report on an investigation of the temperature-dependent ordering of the hydrogen/deuterium atoms in geometrically frustrated magnets Co 2 (OH) 3 Br and its deuterated Co 2 (OD) 3 Br, to shed light on the origin of the newly-identified ferroelectricity using Raman spectroscopy. Significant changes in the Raman frequencies and line-widths of the Raman-active modes were observed below ∼260 K in Co 2 (OD) 3 Br and ∼240 K in Co 2 (OH) 3 Br, respectively, the analysis of which revealed strong spin–phonon couplings in this system. Further, for Co 2 (OD) 3 Br, six new phonon bands appeared below around 260 K, with the corresponding intensities obeying a power-law equation I ∝ 1 − T / T c 2 β wherein T c = 260 K, suggesting that an ordering process occurred below ∼260 K. The ordering process subsequently affected the local structure and brought out the reported ferroelectric phase, which is considered as frustrated. Meanwhile, in Co 2 (OH) 3 Br, only one new band was observed below ∼240 K, followed by two ‘softened’ modes correlated to the [OH] sub-lattice below ∼185 K, wherein an incomplete ordering was suggested. The present work reveals a new multiferroic system combining geometrically frustrated magnetism and deuterium ordering-type ferroelectricity.
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