High-Field Magnetoelectric and Spin-Phonon Coupling in Multiferroic (NH 4 ) 2 [FeCl 5 ·(H 2 O)]
High-Field Magnetoelectric and Spin-Phonon Coupling in Multiferroic (NH 4 ) 2 [FeCl 5 ·(H 2 O)]
复制标题
多铁性(NH 4 ) 2 [FeCl 5 ·(H 2 O)]中的高场磁电和自旋声子耦合
DOI：
10.1021/acs.inorgchem.1c03311
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发表时间：
2022
影响因子：
4.6
通讯作者：
Zapf, Vivien S.
中科院分区：
文献类型：
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作者：
Hughey, Kendall D.;Lee, Minseong;Nam, Jisoo;Clune, Amanda J.;O’Neal, Kenneth R.;Tian, Wei;Fishman, Randy S.;Ozerov, Mykhaylo;Lee, JunHee;Zapf, Vivien S.
我们结合联合收割机的高场极化、磁红外光谱和晶格动力学计算，并结合预先磁化来探讨（NH 4）2[FeCl 5·（H2O）]的性质。（NH 4）2[FeCl 5·（H2O）]是一种II型分子多铁性材料，其中电荷、结构和磁性之间的混合由分子间氢键和卤键控制。电极化是敏感的一系列的场致自旋重新取向，线性增加的字段和达到最大值之前崩溃到零的准共线到共线正弦重新取向由于反转对称的恢复。在1.5K时，P_（10）c，H_（10）c组态在5 ~ 25 T之间的磁电耦合为1.2ps/m量级。在这个范围内，耦合通过轨道杂化机制发生。在（NH 4）2[FeCl 5·（H2O）]中，其他形式的混合也是活跃的。磁红外光谱表明，在30 T下，所有低于600 cm-1的振动模都对场致磁饱和态的跃迁敏感.我们分析了这些局部晶格畸变，并使用频移提取自旋-声子耦合常数的Fe-O伸缩，Fe-OH 2 rock，和NH 4+振动。检查还揭示了铵反离子在铁电转变过程中的微妙对称性破缺。这种不同的混合过程在一个平台上与分子间的氢键和卤素键合的共存打开了大门，以更好地理解多铁性和磁电管通过空间相互作用。
We combine high field polarization, magneto-infrared spectroscopy, and lattice dynamics calculations with prior magnetization to explore the properties of (NH4)2[FeCl5·(H2O)]─a type II molecular multiferroic in which the mixing between charge, structure, and magnetism is controlled by intermolecular hydrogen and halogen bonds. Electric polarization is sensitive to the series of field-induced spin reorientations, increasing linearly with the field and reaching a maximum before collapsing to zero across the quasi-collinear to collinear-sinusoidal reorientation due to the restoration of inversion symmetry. Magnetoelectric coupling is on the order of 1.2 ps/m for theP∥c,H∥cconfiguration between 5 and 25 T at 1.5 K. In this range, the coupling takes place via an orbital hybridization mechanism. Other forms of mixing are active in (NH4)2[FeCl5·(H2O)] as well. Magneto-infrared spectroscopy reveals that all of the vibrational modes below 600 cm–1are sensitive to the field-induced transition to the fully saturated magnetic state at 30 T. We analyze these local lattice distortions and use frequency shifts to extract spin-phonon coupling constants for the Fe–O stretch, Fe–OH2rock, and NH4+libration. Inspection also reveals subtle symmetry breaking of the ammonium counterions across the ferroelectric transition. The coexistence of such varied mixing processes in a platform with intermolecular hydrogen- and halogen-bonding opens the door to greater understanding of multiferroics and magnetoelectrics governed by through-space interactions.