Topological currents in black phosphorus with broken inversion symmetry

TL;DR

This paper investigates how breaking inversion symmetry in black phosphorus induces topological currents, revealing anisotropic and nonlinear effects that depend on crystal orientation, with potential implications for electronic applications.

Contribution

It demonstrates the emergence of topological currents in black phosphorus due to broken inversion symmetry and characterizes their anisotropic and nonlinear behavior.

Findings

Topological currents are maximized along zigzag axes.

Currents are zero along armchair directions.

Both linear transverse and nonlinear charge currents are observed.

Abstract

We examine the nature of topological currents in black phosphorus when its inversion symmetry is deliberately broken. Here, the conduction and valence band edges are located at the $\Gamma$ point of the rectangular Brillouin zone, and they exhibit strong anisotropy along its two crystal axes. We will show below that these salient features lead to a linear transverse neutral topological currents, accompanied also by a non-linear transverse charge current at the Fermi surface. These topological currents are maximal when the in-plane electric field is applied along the zigzag crystal axes, but zero along the armchair direction.