Successive antiferromagnetic transitions with multi- k and noncoplanar spin order, spin fluctuations, and field-induced phases in deformed pyrochlore compound Co2 (OH)3 Br
Successive antiferromagnetic transitions with multi- k and noncoplanar spin order, spin fluctuations, and field-induced phases in deformed pyrochlore compound Co2 (OH)3 Br
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DOI：
10.1103/physrevb.82.214424
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发表时间：
2010-12
影响因子：
3.7
通讯作者：
M. Hagihala;Xu-Guang Zheng;T. Kawae;Taku J. Sato
中科院分区：
文献类型：
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作者：
M. Hagihala;Xu-Guang Zheng;T. Kawae;Taku J. Sato
菱面体结构化合物是几何受挫系列化合物的一员，其中磁性离子形成变形的烧绿石晶格，利用直流和交流磁化率、热容量、中子粉末衍射和μ子自旋旋转/弛豫测量研究了菱面体结构化合物的结构和磁性能。其结构特点是完美的戈薇晶格面和三角形晶格面交替堆叠，沿堆叠方向（轴）有10%的畸变。尽管畸变差异非常小[0.42%大]，但发现显示出与先前报道的铁磁性截然不同的反铁磁性。分别在 和 处观察到连续的反铁磁转变。反铁磁基态是亚稳态的，并且通过施加相对较低的磁场感应出中间磁相。当磁场进一步增加自旋上方时，会发生重新取向，形成类似于铁磁的结构。发现零场中的连续反铁磁转变在传播矢量 k1=(0 −1/2 1/2) at 和附加 k2=(0 0 3/2) at 时发生。中子粉末衍射图案的细化揭示了反铁磁相的非常规多 k 和非共面自旋结构。多次测量，特别是这项研究，一致证明了高温下的磁耦合，以及远低于温度的持续波动。这项工作提出了一个独特的系统来研究轨道效应和晶格畸变在几何挫败中的关键作用，并提供了一个单一的材料系统来研究多个相变和竞争交换相互作用。
Structure and magnetic properties of the rhombohedral-structure compound, a member of the geometrically frustrated series of the compoundswhere the magnetic ions form a deformed pyrochlore lattice, were studied using dc and ac magnetic susceptibilities, heat-capacity, neutron powder-diffraction, and muon-spin-rotation/-relaxationmeasurements. The structure ofis featured by alternatively stacked layers of perfect kagome-lattice planes and triangular-lattice planes with a 10% distortion along the stacking direction (theaxis). Despite a very small difference in the distortion [0.42% larger in],was found to show contrasting antiferromagnetism that is strikingly different from the previously reported ferromagnetic. Successive antiferromagnetic transition was observed atand, respectively. The antiferromagnetic ground state is metastable and an intermediate magnetic phase was induced by applying a relatively low magnetic field of. When the field was further increased abovespin reorientation occurred to form a configuration similar to ferromagnetic. The successive antiferromagnetic transitions in zero field were found to occur with propagation vector of k1=(0 −1/2 1/2) atand an additional k2=(0 0 3/2) at. Refinement of the neutron powder-diffraction patterns revealed an unconventional multi-k and noncoplanar spin structure for the antiferromagnetic phases. Multiple measurements, in particular, thestudy, consistently demonstrated magnetic coupling at high temperatures, and persistent fluctuations well below the. This work presents a unique system to investigate the orbital effect and the critical role of lattice distortion in geometric frustration, and provides a single material system to study multiple phase transitions and competing exchange interactions.