Unoccupied electronic band structure of the semi-metallic Bi(111) surface probed with two-photon photoemission

TL;DR

This study uses two-photon photoemission to directly measure the unoccupied electronic band structure of Bi(111), providing insights relevant to topological insulators and spintronics.

Contribution

It presents the first direct measurement of the unoccupied bands of Bi(111) surface, including bulk, surface, and image potential states.

Findings

Mapped unoccupied p bands of Bi(111)

Identified surface and image potential states

Provided data relevant for topological insulator research

Abstract

While many photoemission studies have dealt with both the bulk band structure and various surface states and resonances, the unoccupied electronic structure above the Fermi level of the Bi(111) surface has not yet been measured directly although understanding of this model semi-metal is of great interest for topological insulators, spintronics and related fields. We use angle-resolved two-photon photoemission to directly investigate the occupied and unoccupied p bands of Bi, including the bulk hole pocket at the T point, as well as the image potential states and surface states of Bi(111).