1. valley hall effect caused by the drag effect in two-dimensional crystals

Leonid Golub

Ioffe Institute, St. Petersburg, Russia

8 December 2020 Tue 4 pm

                                      IBS Center for Theoretical Physics of Complex Systems (PCS), Administrative Office (B349), Theory Wing, 3rd floor

                                      Expo-ro 55, Yuseong-gu, Daejeon, South Korea, 34126 Tel: +82-42-878-8633                     

Valley Hall effect is an appearance of oppositely directed fluxes in two valleys of the Brillouine zone. The valley flux is perpendicular to the initial flux of particles in analogy to the spin Hall effect where the spin current is perpendicular to the electric current. The initial flux can be induced by an external field and temperature gradient or caused by drag of charge particles and excitons by phonons or photons. The aim of the talk is to present a theory of the valley Hall effect in two-dimensional crystals in the drag conditions developed in Refs. [1,2].

It is shown that there are three contributions to the valley currents: (i) the skew-scattering contribution and the anomalous contributions caused by (ii) side jumps of the wavepackets at scattering and (iii) anomalous velocity. Partial cancellation of the anomalous contributions is demonstrated and the physical reason for this cancellation is discussed. For excitons, the drift-diffusion model is generalized taking into account the valley degrees of freedom. Spatial profiles of exciton density and valley polarization are calculated.

[1] Valley Hall effect caused by the phonon and photon drag, M. M. Glazov and L. E. Golub, Phys. Rev. B 102, 155302 (1-16) (2020).

[2] Skew Scattering and Side Jump Drive Exciton Valley Hall Effect in Two-Dimensional Crystals, M. M. Glazov and L. E. Golub, Phys. Rev. Lett. 125, 157403 (1-7) (2020).