Visualizing superconductivity in an inversion-symmetry-broken doped Weyl semimetal

TL;DR

This study uses scanning tunneling microscopy to visualize and analyze the coexistence of superconductivity and Weyl physics in doped MoTe$_2$ with broken inversion symmetry, revealing robust topological superconductivity.

Contribution

It provides the first microscopic visualization of superconductivity coexisting with the Weyl phase in doped MoTe$_2$, highlighting the role of inversion symmetry breaking.

Findings

Superconductivity coexists with the Td Weyl phase in MoTe$_{1.85}$Se$_{0.15}$.

Superconducting coherence length exceeds dopant disorder length scale.

Robust topological superconductivity is observed in the doped Weyl semimetal.

Abstract

The Weyl semimetal MoTe$_2$ offers a rare opportunity to study the interplay between Weyl physics and superconductivity. Recent studies have found that Se substitution can boost the superconductivity up to 1.5K, but suppress the Td structure phase that is essential for the emergence of Weyl state. A microscopic understanding of possible coexistence of enhanced superconductivity and the Td phase has not been established so far. Here, we use scanning tunneling microscopy (STM) to study a optimally doped new superconductor MoTe$_{1.85}$Se$_{0.15}$ with bulk Tc ~ 1.5K. By means of quasiparticle interference imaging, we identify the existence of low temperature Td phase with broken inversion symmetry where superconductivity globally coexists. Consistently, we find that the superconducting coherence length, extracted from both the upper critical field and the decay of density of states near a vortex, is much larger than the characteristic length scale of existing dopant derived chemical disorder. Our findings of robust superconductivity arising from a Weyl semimetal normal phase in MoTe$_{1.85}$Se$_{0.15}$, makes it a promising candidate for realizing topological superconductivity.