Selective observation of surface and bulk bands in polar WTe2 by laser-based spin- and angle-resolved photoemission spectroscopy

TL;DR

This study uses laser-based spin- and angle-resolved photoemission spectroscopy to investigate surface and bulk electronic states in WTe2, revealing Fermi arcs, surface resonance bands, and discrepancies with theoretical calculations.

Contribution

It demonstrates selective observation of surface and bulk bands in WTe2 using SARPES, highlighting the origin of Fermi arcs and surface resonance bands.

Findings

Fermi arcs observed on both surfaces originate from surface states

A surface resonance band connects with Fermi-arc bands, forming a Dirac-cone-like dispersion

Bulk electron and hole bands are closer in momentum space than predicted by calculations

Abstract

The electronic state of WTe2, a candidate of type-II Weyl semimetal, is investigated by using laser-based spin- and angle-resolved photoemission spectroscopy (SARPES). We prepare the pair of WTe2 samples, one with (001) surface and the other with (00-1) surface, by "sandwich method", and measure the band structures of each surface separately. The Fermi arcs are observed on both surfaces. We identify that the Fermi arcs on the two surfaces are both originating from surface states. We further find a surface resonance band, which connects with the Fermi-arc band, forming a Dirac-cone-like band dispersion. Our results indicate that the bulk electron and hole bands are much closer in momentum space than band calculations.