Mechanical control of crystal symmetry and superconductivity in Weyl semimetal MoTe$_2$

TL;DR

This study demonstrates that applying mechanical stress can control the crystal symmetry of MoTe$_2$, influencing its superconducting properties and potentially tuning its topological electronic states.

Contribution

It introduces a method to mechanically manipulate the crystal symmetry of MoTe$_2$, enabling control over its topological and superconducting phases.

Findings

Coexistence of centrosymmetric and non-centrosymmetric phases in superconducting MoTe$_2$

Mechanical stress can switch the crystal structure between different symmetries

Electron-phonon coupling strength is similar across phases

Abstract

The non-centrosymmetric Weyl semimetal candidate, MoTe$_2$ was investigated through neutron diffraction and transport measurements at pressures up to 1.5 GPa and at temperatures down to 40 mK. Centrosymmetric and non-centrosymmetric structural phases were found to coexist in the superconducting state. Density Functional Theory (DFT) calculations reveal that the strength of the electron-phonon coupling is similar for both crystal structures. Furthermore, it was found that by controlling non-hydrostatic components of stress, it is possible to mechanically control the ground state crystal structure. This allows for the tuning of crystal symmetry in the superconducting phase from centrosymmetric to non-centrosymmetric. DFT calculations support this strain control of crystal structure. This mechanical control of crystal symmetry gives a route to tuning the band topology of MoTe$_2$ and possibly the topology of the superconducting state.