We report on an investigation of the temperature-dependent ordering of the hydrogen/deuterium atoms in geometrically frustrated magnets Co₂(OH)₃Br and its deuterated Co₂(OD)₃Br, 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 ∼260K in Co₂(OD)₃Br and ∼240K in Co₂(OH)₃Br, respectively, the analysis of which revealed strong spin–phonon couplings in this system. Further, for Co₂(OD)₃Br, six new phonon bands appeared below around 260K, with the corresponding intensities obeying a power-law equation wherein T _c = 260K, suggesting that an ordering process occurred below ∼260K. The ordering process subsequently affected the local structure and brought out the reported ferroelectric phase, which is considered as frustrated. Meanwhile, in Co₂(OH)₃Br, only one new band was observed below ∼240K, followed by two ‘softened’ modes correlated to the [OH] sub-lattice below ∼185K, wherein an incomplete ordering was suggested. The present work reveals a new multiferroic system combining geometrically frustrated magnetism and deuterium ordering-type ferroelectricity.

我们报告了对几何受挫磁体 Co ₂ (OH) ₃ Br 及其氘化 Co ₂ (OD) ₃ Br 中氢/氘原子的温度依赖性排序的研究，以阐明新鉴定的起源使用拉曼光谱的铁电性。分别在 Co ₂ (OD) ₃ Br 中低于~260K和 Co ₂ (OH) ₃ Br中~240K 下观察到拉曼活性模式的拉曼频率和线宽的显着变化，其分析显示强自旋-该系统中的声子耦合。此外，对于 Co ₂ (OD) ₃BR，六个新的声子频带低于周围出现260K，与相应的强度服从幂律方程，其中Ť _Ç = 260K，这表明的排序过程中发生低于~260K。排序过程随后影响了局部结构并带出了所报告的铁电相，这被认为是受挫的。同时，在 Co ₂ (OH) ₃ Br 中，在~240K 以下仅观察到一个新带，随后是与~185K 以下的 [OH] 子晶格相关的两个“软化”模式，其中表明不完全排序。目前的工作揭示了一种新的多铁系统，它结合了几何受挫磁力和氘有序型铁电性。