High-pressure topological transport study of Bi2Se3 single crystal
High-pressure topological transport study of Bi2Se3 single crystal
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DOI：
10.1016/j.apsusc.2019.145052
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发表时间：
2020-03
影响因子：
6.7
通讯作者：
Junkai Zhang;Yan Zhang;Xiaoxin Wu;Renquan Guan;Ji Li;C. Gao;Qinglin Wang;Yanzhang Ma;Zhao Zh
中科院分区：
文献类型：
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作者：
Junkai Zhang;Yan Zhang;Xiaoxin Wu;Renquan Guan;Ji Li;C. Gao;Qinglin Wang;Yanzhang Ma;Zhao Zh
本文采用交流阻抗谱和直流电导法相结合的方法，研究了理想的拓扑绝缘体Bi2Se3单晶在室温下的拓扑输运。根据样品对电激励响应的不同，样品的绝缘体态和金属表面态可以很好地划分为两个驰豫过程。我们发现，在体态电导率增加一个数量级的情况下，表面态电导率保持不变。采用第一性原理计算来考虑散货运输的结果。能带结构计算表明，随着压强的升高，本征带隙逐渐减小。电荷密度差的变化表明，由于高压下晶格收缩，电子重叠，原子间相互作用增强，形成了小极化子。根据电学参数的压力依赖性及其相互关系，建立了合理的拓扑绝缘子电学模型，为探索极端条件下的拓扑结构开辟了一条新的途径。
Herein we report the topological transport on compressed Bi2Se3single crystal, one of ideally topological insulators, based on a combination of in-situ alternating current (AC) impedance spectra and direct current (DC) conductivity methods at room temperature. The insulating bulk and metallic surface states of the sample are well divided into two relaxation processes according to their different responses on electric excitation. We find that the surface state conductivity remains constant in the face of one order of magnitude increase in the bulk state conductivity. The first-principles calculations are adopted to account for the bulk transport results. The band structures calculations reveal the gradual decrease in the intrinsic bandgap with pressure elevation. The variations of charge density difference demonstrate the strengthened interatomic interactions and the formation of small polarons due to the electrons overlap assisted by the lattice shrinking under high pressure. By the pressure dependences of electrical parameters and the relationship between them, a reasonable electrical model of topological insulators is well established and opens up a new way for the exploration of topological architectures under extreme conditions.