Weyl semimetals and frustrated magnetism
The active field of topological properties of matter has originally been focused on insulators and superconductors with full energy gaps in the bulk. Such systems have robust surface states protected by bulk topological invariants. However, it has become clear that systems with incomplete energy gaps can also have topological invariants and interesting surface states. We are working on Weyl semimetals, in which the electrons in the bulk behave like massless relativistic fermions with their spin locked to their momentum. They are expected to show interesting magnetoelectric response and surface states in the form of open Fermi arcs.
Weyl semimetals have been proposed to arise in magnetically frustrated pyrochlore iridates, which makes them relevant for our Collaborative Research Center 1143. They have recently been realized experimentally in a number of magnetic and nonmagnetic compounds. We are studying the stability of Weyl phases against breaking of symmetries, the possible destruction of surface states by interactions, and bulk and surface transport in Weyl semimetals.
