Observation of spin-polarized bands and domain-dependent Fermi arcs in polar Weyl semimetal MoTe$_2$

TL;DR

This study reveals domain-dependent surface electronic structures and Fermi arc patterns in polar Weyl semimetal MoTe2, combining ARPES measurements with first-principles calculations to elucidate the material's topological features.

Contribution

It provides the first direct observation of domain-dependent Fermi arcs and spin polarizations in polar MoTe2, linking surface states to bulk polarity and Weyl node connections.

Findings

Different surface band dispersions in two domains

Opposite spin polarizations indicating opposite bulk polarity

Distinct Fermi arc patterns consistent with surface calculations

Abstract

We investigate the surface electronic structures of polar 1T'-MoTe2, the Weyl semimetal candidate realized through the nonpolar-polar structural phase transition, by utilizing the laser angle-resolved photoemission spectroscopy (ARPES) combined with first-principles calculations. Two kinds of domains with different surface band dispersions are observed from a single-crystalline sample. The spin-resolved measurements further reveal that the spin polarizations of the surface and the bulk-derived states show the different domain-dependences, indicating the opposite bulk polarity. For both domains, some segment-like band features resembling the Fermi arcs are clearly observed. The patterns of the arcs present the marked contrast between the two domains, respectively agreeing well with the slab calculation of (0 0 1) and (0 0 -1) surfaces. The present result strongly suggests that the Fermi arc connects the identical pair of Weyl nodes on one side of the polar crystal surface, whereas it connects between the different pairs of Weyl nodes on the other side.