One-dimensional half-metallic interfaces of two-dimensional honeycomb insulators

TL;DR

This paper investigates zigzag interfaces in 2D honeycomb insulators, revealing their polar nature, charge transfer mechanisms, and the emergence of one-dimensional ferromagnetic half-metallic states.

Contribution

It demonstrates that these interfaces are inherently polar with charge densities determined by formal valence charges and predicts the formation of 1D ferromagnetic half-metallic states.

Findings

Interfaces are polar with charge densities from formal valence charges.

Charge transfer occurs via a Zener-like mechanism.

Emergence of ferromagnetic half-metallic 1D states.

Abstract

We study zigzag interfaces between insulating compounds that are isostructural to graphene, specifically II-VI, III-V and IV-IV two-dimensional (2D) honeycomb insulators. We show that these one-dimensional interfaces are polar, with a net density of excess charge that can be simply determined by using the ideal (integer) formal valence charges, regardless of the predominant covalent character of the bonding in these materials. We justify this finding on fundamental physical grounds, by analyzing the topology of the formal polarization lattice in the parent bulk materials. First principles calculations elucidate an electronic compensation mechanism not dissimilar to oxide interfaces, which is triggered by a Zener-like charge transfer between interfaces of opposite polarity. In particular, we predict the emergence of one dimensional electron and hole gases (1DEG), which in some cases are ferromagnetic half-metallic.