# CMT Seminar: Interaction induced topological insulators

Monday, May 10, 2010 – 3:15pm

Reiss 261A

Kai Sun

University of Maryland

In the light of recent progress in the search for topologically nontrivial states of matter, discovering and/or understanding new mechanisms which could stabilize these exotic states has become increasingly important. Among the most well-studied examples of the topologically nontrivial insulators, the driven mechanism involves either an external magnetic field or strong spin-orbital effects, while interactions are irrelevant and can be largely ignored. In this talk, I will demonstrate that even in the absence of a magnetic field and spin-orbital coupling, the same topological phases can be induced by interaction effects through spontaneous symmetry breaking. In particular, I will present the asymptotically exact study of two different interacting systems (a 2D zero-gap semi-conductor and a 3D metal), where the topologically nontrivial insulating phases are stabilized by arbitrarily weak interactions. Experimental implications will also be discussed.

Host: Chris Varney