Experimental observation of topological Fermi arcs in type-II Weyl semimetal MoTe2

TL;DR

This paper provides direct spectroscopic evidence of topological Fermi arcs in the type-II Weyl semimetal MoTe2, confirming its status as the first experimental realization of this novel quantum state and opening avenues for exploring exotic phenomena.

Contribution

It reports the first experimental observation of topological Fermi arcs in the predicted type-II Weyl semimetal MoTe2 using ARPES and STM techniques.

Findings

Confirmation of topological surface states in MoTe2

Observation of Fermi arcs via ARPES

Detection of quasi-particle interference patterns

Abstract

Weyl semimetal is a new quantum state of matter [1-12] hosting the condensed matter physics counterpart of relativisticWeyl fermion [13] originally introduced in high energy physics. The Weyl semimetal realized in the TaAs class features multiple Fermi arcs arising from topological surface states [10, 11, 14-16] and exhibits novel quantum phenomena, e.g., chiral anomaly induced negative mag-netoresistance [17-19] and possibly emergent supersymmetry [20]. Recently it was proposed theoretically that a new type (type-II) of Weyl fermion [21], which does not have counterpart in high energy physics due to the breaking of Lorentz invariance, can emerge as topologically-protected touching between electron and hole pockets. Here, we report direct spectroscopic evidence of topological Fermi arcs in the predicted type-II Weyl semimetal MoTe2 [22-24]. The topological surface states are confirmed by directly observing the surface states using bulk-and surface-sensitive angle-resolved photoemission spectroscopy (ARPES), and the quasi-particle interference (QPI) pattern between the two putative Fermi arcs in scanning tunneling microscopy (STM). Our work establishes MoTe2 as the first experimental realization of type-II Weyl semimetal, and opens up new opportunities for probing novel phenomena such as exotic magneto-transport [21] in type-II Weyl semimetals.