Electronic Structure of a Two-Dimensional Graphene-Like Topological Insulator, Bi14Rh3I9

TL;DR

This paper investigates the electronic properties of the newly synthesized two-dimensional topological insulator Bi14Rh3I9, revealing its potential to exhibit quantum spin and valley Hall effects due to strong spin-orbit coupling.

Contribution

The study derives an effective Hamiltonian for Bi14Rh3I9, demonstrating how spin-orbit interaction opens a bandgap and induces topological electronic states in this graphene-like material.

Findings

Spin-orbit coupling opens a 2400 K bandgap at Dirac points.

Bi14Rh3I9 exhibits quantum spin Hall effect.

Potential for quantum valley and spin Hall effects.

Abstract

Very recently, a new two-dimensional graphene-like topological insulator, Bi14Rh3I9, has been synthesized. The Bi-Rh sheets with a strong spin-orbit interaction are graphene analogues with a honeycomb net composed of RhBi8 cubes. Here we derive the low-energy effective Hamiltonian involving spin-orbit coupling for Bi14Rh3I9. In the absence of spin-orbit coupling, the Bi-Rh sheets show two inequivalent Dirac cones at the corners of the hexagonal Brillouin zone. The spin-orbit interaction opens a 2400 K bandgap at the Dirac points and establishes the quantum spin Hall effect in the Bi-Rh sheets. Our result indicates that the Bi14Rh3I9 may combine many unique electronic properties of graphene and topological insulators, and it should host a combination of quantum valley and spin Hall effects.