Lecture (No 201701)

Title： Transport and optical studies in topological materials with Dirac valleys

Speaker: Dr. Wenyu SHAN (CarnegieMellonUniversity)

Time: Thursday, March 2, 15:00

Venue: Room 213, PhysicsBuilding, Wushan Campus

Topological materials have attracted much recent interest from both theoretical and experimental sides. The existence of Dirac valleys gives rise to exotic transport and optical properties. In this talk, I will focus on two types of systems: two-dimensional materials and topological insulators. For two-dimensional materials, I will introduce recent puzzles on valley Hall experiment and our solutions. After that I will talk about the spin Hall effect and optical phenomena in monolayer MoS2. Furthermore I will show the photo-Nernst studies in graphene superlattice. For topological insulators, I predict the band gap opening of Dirac surface states due to finite-size effect, which is later demonstrated by experiments. Based on this, I construct an effective description of topological insulator thin film. I also study the weak-localization effect of Dirac valleys.