Phys :
Seminars /
26.09.2013 - A.P. Balachandran : Edge States: Topological Insulators and Superconductors

**A.P. Balachandran** *Dept. Physics, Syracuse University, USA*

26 September 2013, Thursday, 14:40

Cavid Erginsoy Seminar Room, Physics Department, 3rd floor

**Abstract:**
Let M be a manifold with boundary ∂M. Let it be occupied by a superconductor with ( London) mass m > 0 for the electromagnetic field. We show that there are low-lying edge states with energies small compared to the energy gap m in the bulk . The system preserves parity (P- )and time reversal(T-) invariance. An associated set of edge states occurs for the Dirac operator D for mass m. Its self- adjointness requires an Atiyah-Patodi-Singer (APS) boundary condition. When it is appropriately chosen, D also has low-lying P -and T-invariant edge states, the spinor analogues of the electromagnetic edge states. Further there is spin- momentum locking. All this suggests that these edge states may provide a description of the edge states of topological insulators. The edge states above occur in all spatial dimensions.

**Reminder:** Tea and cookies will be in the seminar room before the seminar.

(Printable View of http://www.physics.metu.edu.tr/Seminars/SEM13048)