# Quasiparticle Interference of Surface States in Type-II Weyl Semimetal WTe$_2$

## TL;DR

This study uses spectroscopic imaging and first-principles calculations to investigate surface states in WTe$_2$, providing evidence of quasiparticle interference and surface state scattering, but not conclusively confirming bulk Type-II Weyl points.

## Contribution

It offers the first combined experimental and theoretical analysis of surface states in WTe$_2$, clarifying quasiparticle interference features and surface scattering phenomena.

## Key findings

- Clear quasiparticle interference features of surface states
- Evidence of surface state scattering in WTe$_2$
- Observation of surface Fermi arcs without definitive proof of Type-II Weyl points

## Abstract

Topological Weyl semimetal (TWS) is a metal, where low energy excitations behave like Weyl fermions of high-energy physics. It was recently shown that due to the lower symmetry of condensed matter systems, they can realize two distinct types of Weyl fermions. The type-I Weyl fermion in a metal is formed by a linear crossing of two bands at a point in the crystalline momentum space - Brillouin zone (BZ). The second type TWSs host type-II Weyl points appearing at the touching points of electron and hole pockets, which is a result of tilted linear dispersion. The type-II TWS was predicted to exist in several compounds, including WTe$_2$. Several ARPES studies of WTe$_2$ were reported so far, having contradictory conclusions on the topological nature of observed Fermi arcs. In this work, we report the results of spectroscopic imaging with a scanning tunneling microscope and first principle calculations, establishing a clear quasiparticle interference features of the surface states of WTe$_2$. Our work provides a strong evidence for surface state scattering. Although the surface Fermi arcs are clearly observed, it is still difficult to prove the existence of predicted Type-II Weyl points in the bulk.