标题： SnTe中拓扑晶体绝缘体的实验实现 显示英文标题

标题： Experimental realization of a topological crystalline insulator in SnTe

摘要： 拓扑绝缘体实现了拓扑量子物质状态，在这种状态下，由时间反演对称性保护的非寻常无能隙金属态出现在边缘或表面。 它们的发现激发了寻找由其他对称性保护的新拓扑状态的研究，最近的理论预测了“拓扑晶体绝缘体”（TCIs）的存在，其中金属表面态由晶体的镜面对称性保护。 然而，其实验验证尚未被报道。 在这里，我们展示了最近被预测为TCI的碲化锡（SnTe）中TCI相的第一个和确定性的实验证据。 我们的角度分辨光电子能谱显示了在SnTe中，金属狄拉克锥形表面带的清晰特征，其狄拉克点略微偏离表面布里渊区的边缘。 另一方面，这种无能隙表面态在同族材料碲化铅（PbTe）中不存在，这与理论预测一致。 我们的结果确立了TCI相的存在，并为奇特的拓扑现象开辟了新的途径。 显示英文摘要

摘要： Topological insulators materialize a topological quantum state of matter where unusual gapless metallic state protected by time-reversal symmetry appears at the edge or surface. Their discovery stimulated the search for new topological states protected by other symmetries, and a recent theory predicted the existence of "topological crystalline insulators" (TCIs) in which the metallic surface states are protected by mirror symmetry of the crystal. However, its experimental verification has not yet been reported. Here we show the first and definitive experimental evidence for the TCI phase in tin telluride (SnTe) which was recently predicted to be a TCI. Our angle-resolved photoemission spectroscopy shows clear signature of a metallic Dirac-cone surface band with its Dirac point slightly away from the edge of the surface Brillouin zone in SnTe. On the other hand, such a gapless surface state is absent in a cousin material lead telluride (PbTe), in line with the theoretical prediction. Our result establishes the presence of a TCI phase, and opens new avenues for exotic topological phenomena.