Signatures of the topological s <sup>+-</sup> superconducting order parameter in the type-II Weyl semimetal T <sub>d</sub>-MoTe<sub>2</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29057874.
- Also identified by DOI 10.1038/s41467-017-01066-6 and PMC identifier 5651900.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
In its orthorhombic T <sub>d</sub> polymorph, MoTe<sub>2</sub> is a type-II Weyl semimetal, where the Weyl fermions emerge at the boundary between electron and hole pockets. Non-saturating magnetoresistance and superconductivity were also observed in T <sub>d</sub>-MoTe<sub>2</sub>. Understanding the superconductivity in T <sub>d</sub>-MoTe<sub>2</sub>, which was proposed to be topologically non-trivial, is of eminent interest. Here, we report high-pressure muon-spin rotation experiments probing the temperature-dependent magnetic penetration depth in T <sub>d</sub>-MoTe<sub>2</sub>. A substantial increase of the superfluid density and a linear scaling with the superconducting critical temperature T <sub>c</sub> is observed under pressure. Moreover, the superconducting order parameter in T <sub>d</sub>-MoTe<sub>2</sub> is determined to have 2-gap s-wave symmetry. We also exclude time-reversal symmetry breaking in the superconducting state with zero-field μSR experiments. Considering the strong suppression of T <sub>c</sub> in MoTe<sub>2</sub> by disorder, we suggest that topologically non-trivial s <sup>+-</sup> state is more likely to be realized in MoTe<sub>2</sub> than the topologically trivial s <sup>++</sup> state.