Neupane Madhab, Xu Su-Yang, Alidoust Nasser, Bian Guang, Kim D J, Liu Chang, Belopolski I, Chang T-R, Jeng H-T, Durakiewicz T, Lin H, Bansil A, Fisk Z, Hasan M Z
Joseph Henry Laboratory and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Department of Physics and Astronomy, University of California at Irvine, Irvine, California 92697, USA.
Phys Rev Lett. 2015 Jan 9;114(1):016403. doi: 10.1103/PhysRevLett.114.016403. Epub 2015 Jan 7.
We present angle-resolved photoemission studies on the rare-earth-hexaboride YbB(6), which has recently been predicted to be a topological Kondo insulator. Our data do not agree with the prediction and instead show that YbB(6) exhibits a novel topological insulator state in the absence of a Kondo mechanism. We find that the Fermi level electronic structure of YbB(6) has three 2D Dirac cone like surface states enclosing the Kramers's points, while the f orbital that would be relevant for the Kondo mechanism is ∼1 eV below the Fermi level. Our first-principles calculation shows that the topological state that we observe in YbB(6) is due to an inversion between Yb d and B p bands. These experimental and theoretical results provide a new approach for realizing novel correlated topological insulator states in rare-earth materials.
我们展示了对稀土六硼化物YbB₆的角分辨光电子能谱研究，最近预测它是一种拓扑近藤绝缘体。我们的数据与该预测不符，相反表明YbB₆在没有近藤机制的情况下呈现出一种新型拓扑绝缘体状态。我们发现YbB₆的费米能级电子结构有三个围绕克莱默斯点的二维狄拉克锥状表面态，而与近藤机制相关的f轨道在费米能级以下约1电子伏特。我们的第一性原理计算表明，我们在YbB₆中观察到的拓扑态是由于Yb的d带和B的p带之间的反转。这些实验和理论结果为在稀土材料中实现新型关联拓扑绝缘体状态提供了一种新方法。
