Signatures of the topological s +− superconducting order parameter in the type-II Weyl semimetal T d-MoTe2

• DOI: 10.1038/s41467-017-01066-6
• Publication Date: 2017-10-16T19:52:06Z
• Authors: Z. Guguchia; F. von Rohr; Z. Shermadini; A. T. Lee; S. Banerjee; A. R. Wieteska; C. A. Marianetti; B. A. Frandsen; H. Luetkens; Z. Gong; S. C. Cheung; C. Baines; A. Shengelaya; G. Taniashvili; A. N. Pasupathy; E. Morenzoni; S. J. L. Billinge; A. Amato; R. J. Cava; R. Khasanov; Y. J. Uemura
• Keywords: Condensed Matter - Materials Science; Science; Condensed Matter - Superconductivity; Q; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; 01 natural sciences; Article; Condensed Matter - Other Condensed Matter; Superconductivity (cond-mat.supr-con); 0103 physical sciences; Other Condensed Matter (cond-mat.other)

AbstractIn its orthorhombic Td polymorph, MoTe2 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 Td-MoTe2. Understanding the superconductivity in Td-MoTe2, 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 Td-MoTe2. A substantial increase of the superfluid density and a linear scaling with the superconducting critical temperature Tc is observed under pressure. Moreover, the superconducting order parameter in Td-MoTe2 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 Tc in MoTe2 by disorder, we suggest that topologically non-trivial s+− state is more likely to be realized in MoTe2 than the topologically trivial s++ state.