Discrete degeneracies distinguished by the anomalous Hall effect in a metallic kagome ice compound
Discrete degeneracies distinguished by the anomalous Hall effect in a metallic kagome ice compound
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DOI：
10.1038/s41567-023-02307-w
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发表时间：
2023-11
期刊：
影响因子：
19.6
通讯作者：
Kan Zhao;Y. Tokiwa;Hua Chen;P. Gegenwart
中科院分区：
文献类型：
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作者：
Kan Zhao;Y. Tokiwa;Hua Chen;P. Gegenwart
在磁性晶体中，尽管时间反演对称性明显破缺，但由时间反演关联的两个平衡态总是能量简并的。在铁磁体中，这种时间反转简并反映在磁化强度的磁场依赖性的磁滞中，并且如果是金属的，则反映在反常霍尔效应（AHE）中。在时间反演中，这两个量都改变了符号，但它们的大小不变。在这里，我们表明，一个时间反演的退化出现在金属戈薇自旋冰HoAgGe时，磁场平行于戈薇平面。我们发现在低温下磁化强度的场依赖性的磁滞消失，但在场依赖性的AHE有限的磁滞。这表明出现了具有几乎相同的能量和净磁化强度，但不同大小的AHE和纵向磁阻的状态。通过分析实验数据和一个最小的紧束缚模型，我们确定了一个时间反转的操作连接这些近简并态，这是有关的非平凡扭曲的kagome晶格HoAgGe。我们的工作证明了输运现象的诊断能力，用于识别受挫自旋系统中隐藏的对称性。
In magnetic crystals, despite the explicit breaking of time-reversal symmetry, two equilibrium states related by time reversal are always energetically degenerate. In ferromagnets, this time-reversal degeneracy is reflected in the hysteresis of the magnetic field dependence of the magnetization and, if metallic, in that of the anomalous Hall effect (AHE). Under time-reversal, both these quantities change signs but not their magnitude. Here we show that a time-reversal-like degeneracy appears in the metallic kagome spin ice HoAgGe when magnetic fields are applied parallel to the kagome plane. We find vanishing hysteresis in the field dependence of the magnetization at low temperature, but finite hysteresis in the field-dependent AHE. This suggests the emergence of states with nearly the same energy and net magnetization but different sizes of the AHE and of the longitudinal magnetoresistance. By analysing the experimental data and a minimal tight-binding model, we identify a time-reversal-like operation connecting these near-degenerate states, which is related to the non-trivial distortion of the kagome lattice in HoAgGe. Our work demonstrates the diagnostic power of transport phenomena for identifying hidden symmetries in frustrated spin systems.