Surface polarization and edge charges

TL;DR

This paper introduces the concept of surface polarization in insulators, formulates it using Berry phase, and demonstrates how it leads to edge and corner charge accumulation in specific lattice models.

Contribution

It defines surface polarization in terms of Berry phase and uses tight binding models to show its physical manifestations at edges and corners.

Findings

Surface polarization can be characterized by Berry phase.

Edge and corner charges are linked to surface polarization.

Demonstrated in 2D lattice models including GaAs.

Abstract

The term "surface polarization" is introduced to describe the in-plane polarization existing at the surface of an insulating crystal when the in-plane surface inversion symmetry is broken. Here, the surface polarization is formulated in terms of a Berry phase, with the hybrid Wannier representation providing a natural basis for study of this effect. Tight binding models are used to demonstrate how the surface polarization reveals itself via the accumulation of charges at the corners/edges for a two dimensional rectangular lattice and for GaAs.