Movable Dirac Points with Ferroelectrics: Kink States and Berry Curvature Dipoles

TL;DR

This paper investigates how ferroelectric polarization can manipulate movable 2D Dirac points, leading to tunable topological phenomena such as kink states and Berry curvature dipoles, with potential experimental signatures in conductance and nonlinear Hall effects.

Contribution

It introduces a novel approach to control topological properties in 2D materials by leveraging ferroelectric polarization to move Dirac points and induce new topological states.

Findings

Identification of materials platforms with movable Dirac points.

Prediction of topological kink states and Berry curvature dipoles.

First-principles results for Cl$_2$Rh$_2$S$_2$-GeS junction supporting the theory.

Abstract

Two-dimensional (2D) Dirac states and Dirac points with linear dispersion are the hallmark of graphene, topological insulators, semimetals, and superconductors. Lowering a symmetry by the ferroelectric polarization opens the gap in Dirac points and introduces finite Berry curvature. Combining this with Dirac points detached from high symmetry points of the Brillouin zone offers additional ways to tailor topological properties. We explore this concept by studying topological phenomena emerging in 2D materials with movable Dirac points and broken out-of-plane mirror reflection. The resulting topological kink states and Berry curvature dipoles are changed by movable 2D Dirac points with experimental signatures in electrical conductance and second-harmonic nonlinear Hall conductivity. We identify materials platforms where our predictions can be realized and support that with the first-principles results for Cl$_2$Rh$_2$S$_2$-GeS junction.