Dirac cone in a non-honeycomb surface alloy

TL;DR

This paper reports the discovery of Dirac cone electronic states in a non-honeycomb surface alloy with an oblique lattice symmetry, expanding the understanding of Dirac physics beyond traditional honeycomb structures.

Contribution

It demonstrates the occurrence of Dirac cones in a non-honeycomb, oblique lattice surface alloy, which is a novel finding in surface science.

Findings

Dirac-like linear bands observed at the zone-center.

First demonstration of Dirac cones in a non-honeycomb 2D surface alloy.

Surface alloy formed by depositing Sn on Au(111) exhibits unique electronic properties.

Abstract

We demonstrate unexpected occurrence of linear bands resembling Dirac cone at the zone-center of Au$_2$Sn surface alloy with $\left( \begin{smallmatrix} 2&1\\ 1&3 \end{smallmatrix} \right)$ surface structure formed by deposition of about 0.9 ML Sn on Au(111) at elevated temperature. The surface exhibits an oblique symmetry with unequal lattice constants making it the first two dimensional surface alloy to exhibit Dirac cone with a non-honeycomb lattice.