Bulk Rotational Symmetry Breaking in Kondo Insulator SmB6
Bulk Rotational Symmetry Breaking in Kondo Insulator SmB6
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DOI：
10.1103/physrevx.7.031054
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发表时间：
2017-09
期刊：
影响因子：
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通讯作者：
Z. Xiang;B. Lawson;T. Asaba;C. Tinsman;Lu Chen;C. Shang;X. Chen;Lu Li
中科院分区：
文献类型：
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作者：
Z. Xiang;B. Lawson;T. Asaba;C. Tinsman;Lu Chen;C. Shang;X. Chen;Lu Li
近藤绝缘体SmB6(SmB6)作为一种潜在的强相关拓扑绝缘体，近年来受到了广泛的研究。在SmB6中观察到的最令人兴奋的现象之一是，尽管SmB6在电阻中具有绝缘行为，但在低温下磁扭矩中出现了明显的量子振荡。这些量子振荡表现出多个频率和不同的有效质量。然而，量子振荡的起源仍在争论中，有证据表明存在二维费米面和三维费米面。在这里，我们在高达45T的磁场和低至40MK的温度范围内进行角度分辨扭矩磁测量。当磁场在(010)面内旋转时，最强振荡分支的量子振荡频率表现出四重旋转对称性。然而，在同一分支振幅的角度依赖关系中，这种四重对称性被打破，而呈现出双重对称性，这与二维Lifshitz-Kosevich模型的预测是一致的。在40mK以下，Lifshitz-Kosevich行为没有观察到偏差。我们的结果表明，SmB6中存在多个轻质量表面态，它们的迁移率明显取决于表面无序能级。
Kondo insulator samarium hexaboride (SmB6) has been intensely studied in recent years as a potential candidate of a strongly correlated topological insulator. One of the most exciting phenomena observed in SmB6 is the clear quantum oscillations appearing in magnetic torque at a low temperature despite the insulating behavior in resistance. These quantum oscillations show multiple frequencies and varied effective masses. The origin of quantum oscillation is, however, still under debate with evidence of both two-dimensional Fermi surfaces and three-dimensional Fermi surfaces. Here, we carry out angle-resolved torque magnetometry measurements in a magnetic field up to 45 T and a temperature range down to 40 mK. With the magnetic field rotated in the (010) plane, the quantum oscillation frequency of the strongest oscillation branch shows a four-fold rotational symmetry. However, in the angular dependence of the amplitude of the same branch, this four-fold symmetry is broken and, instead, a twofold symmetry shows up, which is consistent with the prediction of a two-dimensional Lifshitz-Kosevich model. No deviation of Lifshitz-Kosevich behavior is observed down to 40 mK. Our results suggest the existence of multiple light-mass surface states in SmB6, with their mobility significantly depending on the surface disorder level.