Topological band structure transitions in honeycomb antimonene as function of buckling

TL;DR

This study explores how the topological electronic properties of monolayer antimonene change with buckling, revealing transitions from Dirac semimetal to trivial semiconductor through first-principles calculations and effective models.

Contribution

It provides a detailed analysis of topological phase transitions in antimonene as a function of buckling, combining first-principles and theoretical modeling.

Findings

Buckling induces a transition from Dirac semimetal to trivial semiconductor.

A nodal line with anisotropic transport properties is identified in flat antimonene.

Critical buckling angles lead to the annihilation of Dirac points and topological phase change.

Abstract

The electronic band topology of monolayer $\beta$-Sb (antimonene) is studied from the flat honeycomb to the equilibrium buckled structure using first-principles calculations and analyzed using a tight-binding model and low energy Hamiltonians. In flat monolayer Sb, the Fermi level occurs near the intersection of two warped Dirac cones, one associated with the $p_z$-orbitals, and one with the $\{p_x,p_y\}$-orbitals. The differently oriented threefold warping of these two cones leads to an unusually shaped nodal line, which leads to anisotropic in-plane transport properties and goniopolarity. A slight buckling opens a gap along the nodal line except at six remaining Dirac points, protected by symmetry. Under increasing buckling, pairs of Dirac points of opposite winding number annihilate at a critical buckling angle. At a second critical angle, the remaining Dirac points disappear when the band structure becomes a trivial semiconductor. Spin-orbit coupling and edge states are discussed.