Studies of various types of Hall eﬀects have led to great advances in solid state physics. In this talk, I will describe two novel Hall phenomena. The first is thermoelectric Hall effect that describes the generation of a transverse electrical current under a temperature gradient. Under a quantizing magnetic field, thermoelectric Hall conductivity is proportional to thermal entropy which is strongly enhanced by Landau level degeneracy. This leads to an unbounded growth of the thermopower in three- dimensional Dirac/Weyl semimetals, a parametrically large thermoelectric figure of merit in quantum Hall systems at low temperature, and a new experimental way to study neutral collective modes in the fractional quantum Hall liquids.
Second, I will discuss a nonlinear Hall effect in nonmagnetic materials at zero magnetic field, where the transverse current depends quadratically on the applied electric field. This effect arises from anomalous velocity in a current-carrying state, driven by Berry curvature in inversion-breaking systems.
Aut. Qtr. Colloq. committee: R. Blandford (Chair), B. Feldman, A. Kapitulnik, B. Lev and V. Khemani
Location: Hewlett Teaching Center, Rm. 200