Joseph Henry Laboratory and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
Nat Commun. 2013;4:2991. doi: 10.1038/ncomms3991.
The Kondo insulator SmB6 has long been known to exhibit low-temperature transport anomalies whose origin is of great interest. Here we uniquely access the surface electronic structure of the anomalous transport regime by combining state-of-the-art laser and synchrotron-based angle-resolved photoemission techniques. We observe clear in-gap states (up to ~4 meV), whose temperature dependence is contingent on the Kondo gap formation. In addition, our observed in-gap Fermi surface oddness tied with the Kramers' point topology, their coexistence with the two-dimensional transport anomaly in the Kondo hybridization regime, as well as their robustness against thermal recycling, taken together, collectively provide strong evidence for protected surface metallicity with a Fermi surface whose topology is consistent with the theoretically predicted topological Fermi surface. Our observations of systematic surface electronic structure provide the fundamental electronic parameters for the anomalous Kondo ground state of correlated electron material SmB6.
长期以来，Kondo 绝缘体 SmB6 表现出低温输运异常，其起源引起了广泛关注。在这里，我们结合最先进的激光和基于同步加速器的角分辨光发射技术，独特地研究了反常输运状态下的表面电子结构。我们观察到明显的带隙态（高达约 4meV），其温度依赖性取决于 Kondo 带隙的形成。此外，我们观察到的带隙费米面奇异性与 Kramers 点拓扑相关，它们与 Kondo 杂化区二维输运异常同时存在，以及它们对热循环的稳定性，这些共同为具有 Fermi 面拓扑与理论预测的拓扑 Fermi 面一致的受保护表面金属性提供了有力证据。我们对系统的表面电子结构的观测为相关电子材料 SmB6 的反常 Kondo 基态提供了基本的电子参数。
