#### Special Condensed Matter Seminar, Kai Sun, U of Michigan at Ann Arbor, Kondo insulators: insulator, metal or topological insulator?

In the last few decades, various puzzles have emerged in the study of strongly-correlated materials. In a family of strongly-correlated insulators, known as Kondo insulators, one such long-standing puzzle has remained open for over 40 years. In particular, it has been found that some Kondo insulators display strange electrical transport that cannot be understood if one assumes that it is governed by the three-dimensional bulk. In this talk, I show that some Kondo insulators have the right ingredients to be topological insulators, which we called topological Kondo insulators. For a topological Kondo insulator, the low-temperature transport is dominated by the 2D surface rather than the 3D bulk, because the bulk of this material is an insulator while its surface is a topologically-protected 2D metal. This theoretical picture offers a natural explanation for the long-standing puzzle mentioned above. I will also discuss some recent experiments, which indicate that SmB$_6$ (a Kondo insulator) is indeed a bulk insulator with a conducting surface.

**Location:**
PCTS Seminar Room

**Date/Time: **04/30/13
at
3:30 pm
- 04/30/13
at
5:00 pm

**Category: **Condensed Matter Seminar

**Department: **Physics