Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany and Karlsruhe Institut für Technologie KIT, Gemeinschaftslabor für Nanoanalytik, 76021 Karlsruhe, Germany.
Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany.
Phys Rev Lett. 2014 Jun 6;112(22):226402. doi: 10.1103/PhysRevLett.112.226402. Epub 2014 Jun 5.
Typical Kondo insulators (KIs) can have a nontrivial Z_{2} topology because the energy gap opens at the Fermi energy (E_{F}) by a hybridization between odd- and even-parity bands. SmB_{6} deviates from such KI behavior, and it has been unclear how the insulating phase occurs. Here, we demonstrate that charge fluctuations are the origin of the topological insulating phase in SmB_{6}. Our angle-resolved photoemission spectroscopy results reveal that with decreasing temperature the bottom of the d-f hybridized band at the X[over ¯] point, which is predicted to have odd parity and is required for a topological phase, gradually shifts from below to above E_{F}. We conclude that SmB_{6} is a charge-fluctuating topological insulator.
典型的近藤绝缘体 (Kondo insulator, KI) 可能具有非平凡的 Z_{2}拓扑，因为在费米能 (E_{F}) 处，奇偶带之间的杂化导致能隙打开。SmB_{6} 偏离了这种 KI 行为，其绝缘相的产生机制尚不清楚。在这里，我们证明了电荷涨落是 SmB_{6} 中拓扑绝缘相的起源。我们的角分辨光电子能谱结果表明，随着温度的降低，在 X[over ¯]点处的 d-f 杂化能带的底部逐渐从低于 E_{F}转移到高于 E_{F}，该能带预测具有奇宇称，是拓扑相所必需的。我们得出结论，SmB_{6} 是一种电荷涨落的拓扑绝缘体。
