Département de la Matière Condensée, University of Geneva, CH-1211 Geneva 4, Switzerland.
Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland.
Phys Rev Lett. 2014 Jan 31;112(4):047402. doi: 10.1103/PhysRevLett.112.047402. Epub 2014 Jan 28.
BiTeI is a giant Rashba spin splitting system, in which a noncentrosymmetric topological phase has recently been suggested to appear under high pressure. We investigated the optical properties of this compound, reflectivity and transmission, under pressures up to 15 GPa. The gap feature in the optical conductivity vanishes above p∼9 GPa and does not reappear up to at least 15 GPa. The plasma edge, associated with intrinsically doped charge carriers, is smeared out through a phase transition at 9 GPa. Using high-pressure Raman spectroscopy, we follow the vibrational modes of BiTeI, providing additional clear evidence that the transition at 9 GPa involves a change of crystal structure. This change of crystal structure possibly inhibits the high-pressure topological phase from occurring.
BiTeI 是一个巨大的 Rashba 自旋劈裂系统，最近有人提出在高压下它会出现非中心对称拓扑相。我们研究了该化合物在高达 15 GPa 压力下的光学性质，包括反射率和透过率。在 p∼9 GPa 以上，光学电导率的能隙特征消失，并且至少在 15 GPa 以上也没有重新出现。与本征掺杂载流子相关的等离子体边缘在 9 GPa 的相变过程中变得模糊。我们利用高压拉曼光谱，跟踪 BiTeI 的振动模式，这为相变发生在 9 GPa 提供了额外的明确证据。这种晶体结构的变化可能抑制了高压拓扑相的出现。
