Thermal Hall conductivity in quantum magnets from the kinetic equation

Léo Mangeolle (Technical Unievrsity of Munich)

Thermal Hall conductivity has recently emerged as an experimentally accessible property of insulating materials. Theoretical understanding thereof has remained a challenge, in particular since the breaking of time-reversal symmetry by neutral particles is nontrivial and can emerge from multiple mechanisms (intrinsic semiclassical dynamics, skew-scattering, disorder side-jump effects, etc). In this seminar, I will show that many of these effects can be studied together within a kinetic (Boltzmann-like) formalism. First, I will briefly discuss inelastic skew-scattering of energy-carrying bosons by other collective excitations, with applications to phonon-magnon interactions in antiferromagnets. Second, I will present how anomalous contributions to the semiclassical dynamics of carriers can be incorporated in a rigorous way, yielding the intrinsic thermal Hall effect of chiral bosons (e.g. magnons in frustrated magnets). Finally, I will discuss side-jump phenomena, a mixed effect of disorder scattering and semiclassical dynamics that may explain some puzzling experimental facts.

Contact : S. Capponi