Electron diffusion induced valley Hall effect and nonlinear galvanodiffusive transport in hexagonal 2D Dirac monolayer materials

TL;DR

This paper theoretically investigates diffusion-driven valley Hall and nonlinear galvanodiffusive transport phenomena in hexagonal 2D Dirac monolayer materials, emphasizing anisotropic scattering and electron-density gradient effects.

Contribution

It develops a comprehensive theory for diffusive valley Hall and PGE-like effects in 2D Dirac materials considering anisotropic impurity scattering and electron-density gradients.

Findings

Identification of valley Hall effect driven by electron density gradients.

Analysis of PGE-like nonlinear transport due to valley anisotropy.

Theoretical framework incorporating impurity scattering and electron-density derivatives.

Abstract

Diffusion currents are theoretically examined in two-dimensional Dirac materials, such as those of the transition metal dichalcogenides (TMD) family. The transversal effects are analogues of the valley Hall (VHE) and photogalvanic (PGE) transport phenomena in case when the electron driving force is not an electric field but a gradient of electron density distribution in the sample. The latter can be created by a finite-sized laser spot or by the injection of electrons from other materials. We develop the theory of diffusive VHE effect assuming the anisotropic electron-short-range-impurity skew scattering. The electron PGE-like transport caused by higher electron-density derivatives is analyzed assuming the trigonal warping anisotropy of electron valleys in a TMD monolayer. The nonlinear responses on electron-density gradient are studied as well. The isotropic processes of electron scattering off the short-range and Coulomb centers are taken into account in the PGE-like transport theory.