Searching for topological Fermi arcs via quasiparticle interference on a type-II Weyl semimetal MoTe$_2$

TL;DR

This study uses Fourier transform scanning tunneling spectroscopy and first-principles calculations to identify and analyze topological Fermi arcs and scattering channels in the type-II Weyl semimetal MoTe$_2$, revealing complex surface-bulk interactions.

Contribution

It provides the first combined experimental and theoretical analysis of Fermi arcs and scattering channels in MoTe$_2$, highlighting the effects of broken inversion symmetry.

Findings

Identification of intra-arc scattering signals

Observation of surface-bulk scattering interactions

Broken inversion symmetry alters surface states

Abstract

Weyl semimetals display a novel topological phase of matter where the Weyl nodes emerge in pairs of opposite chirality and can be seen as either a source or a sink of Berry curvature. The exotic effects in Weyl semimetals, such as surface Fermi arcs and the chiral anomaly, make them a new playground for exploring novel functionalities. Further exploiting their potential applications requires clear understanding of their topological electronic properties, such as Weyl points and Fermi arcs. Here we report a Fourier transform scanning tunneling spectroscopy (FT-STS) study on a type-II Weyl semimetal candidate MoTe$_2$ whose Weyl points are predicated to be located above Fermi level. Although its electronic structure below the Fermi level have been identified by angle resolved photo emission spectroscopy (ARPES), by comparing our experimental data with first-principles calculations, we are able to identify the origins of the multiple scattering channels at energies both below and above Fermi level. Our calculations also show the existence of both trivial and topological arc like states above the Fermi energy. In the FT-STS experiments, we have observed strong signals from intra-arc scatterings as well as from the scattering between the arc-like surface states and the projected bulk states. A detailed comparison between our experimental observations and calculated results reveals the trivial and non-trivial scattering channels are difficult to distinguish in this compound. Interestingly, we find that the broken inversion symmetry changes the terminating states on the two inequivalent surfaces, which in turn changes the relative strength of the scattering channels observed in the FT-STS images on the two surfaces.