Realization of a transition between type-I and type-II Dirac semimetals in monolayers

TL;DR

This paper proposes a mechanism to induce a phase transition between type-I and type-II Dirac semimetals in 2D materials through strain, confirmed by first-principles calculations on monolayer PN and AsN.

Contribution

It introduces a novel strain-induced transition mechanism between Dirac semimetal types in 2D materials, supported by first-principles evidence.

Findings

Transition can be achieved in 2D zigzag chain materials by strain.

Monolayer PN and AsN can switch between Dirac types under strain.

A synthesis routine for these 2D structures is proposed.

Abstract

The phase transition between type-I and type-II Dirac semimetals will reveal a series of significant physical properties because of their completely distinct electronic, optical and magnetic properties. However, no mechanism and materials have been proposed to realize the transition to date. Here, we propose that the transition can be realized in two-dimensional (2D) materials consisting of zigzag chains, by tuning external strains. The origination of the transition is that some orbital interactions in zigzag chains vary drastically with structural deformation, which changes dispersions of the corresponding bands. Two 2D nanosheets, monolayer PN and AsN, are searched out to confirm the mechanism by using first-principles calculations. They are intrinsic type-I or type-II Dirac materials, and transit to another type of Dirac materials by external strains. In addition, a possible routine is proposed to synthesize the new 2D structures.