Symmetry-controlled multi-gap superconductivity and higher-order topological phases of MoTe2

Abstract

Abstract The transition-metal dichalcogenide MoTe 2 has been proposed as an ideal platform to intertwine superconductivity with band topology, yet a key experiment—tracking how its properties evolve across a pressure-tuned structural and topological phase transition—has remained elusive. Here, we map the superconducting landscape across these high-pressure regimes from the noncentrosymmetric type-II Weyl semimetal T d phase to the centrosymmetric $$1{{{{\rm{T}}}}}^{{\prime} }$$ 1 T ′ phase using surface-sensitive soft point-contact Andreev spectroscopy combined with quantitative theoretical analysis. In the T d phase, our spectra consistently reveal two distinct superconducting gaps that remain resolvable under an external magnetic field, implying robust and pressure-independent multi-gap superconductivity consistent with muon-spin-rotation evidence for two s -wave gaps at ambient pressure. In the $$1{{{{\rm{T}}}}}^{{\prime} }$$ 1 T ′ phase, reached by pressure along a topological pathway that connects the Weyl to the higher-order topological phase, we observe an s  +  p -wave surface response whose p -wave component follows the s -wave gap in temperature and is rapidly suppressed by a magnetic field—fingerprints of proximity-induced p -wave pairing between a bulk s -wave superconducting band and second-order topological surface states. This phenomenology aligns with theoretical analysis showing that the T d phase hosts type-II Weyl points, whereas the $$1{{{{\rm{T}}}}}^{{\prime} }$$ 1 T ′ phase realizes a higher-order topological insulator arising from double-band inversion. Finally, we further propose that the resulting higher-order hinge boundary channels provide a natural route toward potential zero-energy Majorana corner modes under the observed s  +  p -wave proximity pairing, suggesting MoTe 2 as an intrinsic, pressure-tunable platform for multi-gap and s  +  p -wave topological superconductivity.