Bulk and surface electronic structure of MoAlB(010)

TL;DR

This study combines experimental and computational methods to analyze the electronic structure of MoAlB(010), revealing bulk Fermi surface features and various surface states with Rashba splitting influenced by elemental character.

Contribution

It provides new insights into the surface states and their spin-orbit characteristics of MoAlB(010), supported by combined photoemission spectroscopy and density functional calculations.

Findings

Bulk Fermi surface crossings match previous reports.

Identification of surface states with Rashba-type spin-orbit splitting.

Surface states exhibit symmetry-enforced crossings protected by mirror symmetry.

Abstract

The bulk and surface electronic structure of MoAlB(010) is studied by a combination of angle-resolved photoemission spectroscopy and density functional calculations. The observed bulk Fermi-level crossings agree with the previously reported bulk Fermi surface of the material. Additionally, we find several surface states in the wide projected bulk band gaps around the Fermi energy. The surface states differ in their stability under residual-gas exposure in the vacuum system and in the magnitude of their Rashba-type spin-orbit splitting. We explain this in terms of their elemental and orbital character. A surface state arising from Al dangling bonds is sensitive to surface contamination, whereas a mainly Mo-derived surface state exhibits the stronger spin-orbit splitting. The surface states show symmetry-enforced crossings near the $\bar{\mathrm{S}}$ point of the surface Brillouin zone. These are protected by the mirror-symmetry elements of the p2mm wallpaper group.