Who: Stepan Tsirkin, Physik Institut-Condensed Matter Theory, University of Zurich
Place: Online Seminar, Donostia International Physics Center
Date: Friday, 25 June 2021, 12:00
There has recently been a huge renewed interest to the study of currents generated in solids by external electrical and magnetic fields, especially in relation with topology, Berry curvature and Weyl points. The responses of interest include nonlinear anomalous Hall effect, crystal Hall effect, planar Hall effect, unidirectional magnetoresistance and electrical magnetochiral anisotropy among others. In this talk I will overview and systematize these effects according to their properties with respect to the inversion and time-reversal symmetry, as well as by being Hall-like or Ohmic. In fact, the the very definition of "Hall-like" response is subtle in the nonlinear case, but I will give a solid mathematical ground to such definition. Next, I will show hoe the effects can be systematically described by the Boltzmann equations modified by Berry curvature and intrinsic magnetic moment of Bloch states - the so-called "Berry-Boltzmann" formalism. Finally, I will address some aspects of ab initio evaluation of such responses within Wannier functions formalism, and how we are implementing it in the WannierBerri code.
Host: Daniel Sanchez Portal