DEPARTMENT COLLOQUIUM | Topological Kondo Insulator: The History and Recent Progress on the Study of Samarium Hexaboride (SmB₆)

In this talk, I will discuss the story about solving a 40+ year mystery, in which experimental and theoretical groups in our department have been playing a critical role. In the study of strongly-correlated systems, a long-standing puzzle remained open for over 40 years. For some strongly-correlated heavy fermion insulators (e.g. SmB₆), the electrical transport shows both insulating and conducting signature, and the strange electrical transport cannot be understood no matter whether we assume the material being an insulator or a metal. In this talk, I will discuss recent theoretical and experimental progress that indicates that SmB₆ is a topological Kondo insulator. In contrast to an ordinary three-dimensional insulator, the two-dimensional surface of such a material is a topologically-protected 2D metal. As a result, the low-temperature transport of SmB6 is dominated by its 2D surface rather than the 3D bulk. This result offers a natural explanation for the long-standing puzzle mentioned above, and makes SmB₆ the best candidate for the first ideal 3D topological insulator.