Observation of Fermi arc and its connection with bulk states in the candidate type-II Weyl semimetal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">WTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

Abstract

WTe${}_{2}$ is well known for its manifestation of anomalously large magnetoresistance. It has recently attracted much attention because it is theoretically predicted to be the first material candidate that may realize the ``type-II'' Weyl state. This work reports combined experimental and theoretical investigations on the electronic structure of WTe${}_{2}$. Taking advantage of the latest-generation laser-based angle-resolved photoemission (ARPES) system with superior instrumental resolution, a complete picture of the electronic structure of WTe${}_{2}$ is revealed. The existence of a surface state that connects the bulk electron and hole pockets is identified. High-temperature ARPES measurements make it possible to reveal electronic states above the Fermi level where the Weyl points are predicted to be located. The observed connection of the surface state with the bulk bands, its momentum evolution, and its momentum and energy locations, are all in good agreement with the calculated band structures. These results provide key information to understand the anomalous transport properties of WTe${}_{2}$. They also provide electronic signatures that are consistent with the type-II Weyl state in WTe${}_{2}$ and lay a foundation for further investigations on its topological nature.