Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Center for High Pressure Science &Technology Advanced Research (HPSTAR), Shanghai, China.
Sci Rep. 2017 Jan 4;7:39699. doi: 10.1038/srep39699.
Strong spin orbital interaction (SOI) can induce unique quantum phenomena such as topological insulators, the Rashba effect, or p-wave superconductivity. Combining these three quantum phenomena into a single compound has important scientific implications. Here we report experimental observations of consecutive quantum phase transitions from a Rashba type topological trivial phase to topological insulator state then further proceeding to superconductivity in a SOI compound BiTeI tuned via pressures. The electrical resistivity measurement with V shape change signals the transition from a Rashba type topological trivial to a topological insulator phase at 2 GPa, which is caused by an energy gap close then reopen with band inverse. Superconducting transition appears at 8 GPa with a critical temperature T of 5.3 K. Structure refinements indicate that the consecutive phase transitions are correlated to the changes in the Bi-Te bond and bond angle as function of pressures. The Hall Effect measurements reveal an intimate relationship between superconductivity and the unusual change in carrier density that points to possible unconventional superconductivity.
强自旋轨道相互作用（SOI）可以诱导出独特的量子现象，如拓扑绝缘体、Rashba 效应或 p 波超导性。将这三种量子现象结合在一个单一的化合物中具有重要的科学意义。在这里，我们报告了在通过压力调谐的 SOI 化合物 BiTeI 中，从 Rashba 型拓扑平庸相到拓扑绝缘体态，然后进一步到超导的连续量子相变的实验观察结果。随着 V 形变化的电阻测量信号表明，在 2 GPa 时，从 Rashba 型拓扑平庸到拓扑绝缘体相的转变是由能带反转导致的能隙关闭然后重新打开引起的。在 8 GPa 时出现超导转变，临界温度 T 为 5.3 K。结构精修表明，连续的相变与 Bi-Te 键和键角随压力的变化有关。霍尔效应测量表明，超导性与载流子密度的异常变化密切相关，这表明可能存在非常规超导性。
