Mechanical Control of Crystal Symmetry and Superconductivity in Weyl Semimetal MoTe2

Published: July 30, 2018

Author(s)

Colin A Heikes, I Lin NMN Liu, Tristin Metz, Christoper Eckberg, Paul Michael Neves, Yan Wu, Linda NMN Hung, Phil Piccoli, Huibo Cao, Juscelino Leao, Johnpierre Paglione, Taner Yildirim, Nicholas P. Butch, William D. Ratcliff

Abstract

The concept of topological order applied to condensed matter systems has inspired extensive experimental and theoretical searches for novel types of quantum matter. Topological superconductivity, where a bulk superconducting state and non-trivial topology leads to gapless surface states in a superconducting system, is of particular interest and excitement due to the theoretical prediction of Majorana modes in such a system and the implications for quantum computation with such an excitation [9]. For topological superconductivity, one promising route is susperconductors with broken inversion symmetry, so crystal space groups become immediately relevant in the discussion of new candidates. One material with the potential for topological superconductivity is MoTe, where both a topologically non-trivial type II Weyl semimetallic state and a superconducting state have been reported {1, 2, 4, 6, 10, 11]. The importance of structural symmetry in MoTe2 is two-fold as the Weyl state also requires non-centrosymmetric space groups, and semimetallic MoTe2 shows a structural transition between a centrosymmetric phase at room temperature to a non-centrosymmetric phase below 250 K [2]. A complicating factor is that both the centrosymmetric phase and the superconducting phase appear to be stabilized with pressure, with the superconducting Τc increasing by more than a factor of 10 with the application of relatively small pressures below 2 GPa [1, 2]. The superconductivity in MoTe2 has also been demonstrated to couple strongly to impurity concentrations [4], while both of the superconductivity and the structural transition are modified by Te vacancies [7], W doping onto the Mo sites [5], and S substitution onto the Te sites [12]. Inspired by this, we show that the application of pressure allows us to control the band structure in this material and thus tune the topology of the superconducting state.
Citation: Physical Review Materials
Volume: 2
Issue: 7
Pub Type: Journals

Keywords

Topological Materials, Superconductivity, MoTe2, Quantum Materials, Band Topology
Created July 30, 2018, Updated November 10, 2018