Mixed Triplet-Singlet Order Parameter in Decoupled Superconducting 1H Monolayers of Transition-Metal Dichalcogenides
Abstract
Understanding the emergence of unconventional superconductivity, where the order parameter deviates from simple isotropic s-wave pairing, is a central puzzle in condensed matter physics. Transition-metal dichalcogenides (TMDCs), though generally regarded as conventional superconductors, display signatures of this unusual behavior and thus provide a particularly intriguing platform to explore how exotic states arise. Here we investigate the misfit compound (SnS)(TaS), a heterostructure composed of alternating SnS and 1H-TaS layers. Using transport, photoemission, and scanning tunneling spectroscopy, we demonstrate that the SnS layers effectively decouple the TaS into electronically isolated 1H sheets. In this limit, the tunneling density of states reveals a clear two-gap superconducting spectrum with T 3.1 K. A theoretical model based on lack of inversion symmetry and finite-range attraction reproduces the observed multi-gap structure as a mixed singlet-triplet state. These results establish misfit compounds as a powerful platform for studying unconventional superconductivity in isolated 1H layers and for realizing multiple uncoupled superconductors within a single crystal.
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Cite
@article{arxiv.2509.13303,
title = {Mixed Triplet-Singlet Order Parameter in Decoupled Superconducting 1H Monolayers of Transition-Metal Dichalcogenides},
author = {Avior Almoalem and Sajilesh Kunhiparambath and Roni Anna Gofman and Yuval Nitzav and Ilay Mangel and Nitzan Ragoler and Jun Fujii and Ivana Vobornik and Francois Bertran and Amit Kanigel and Jonathan Ruhman and Vidya Madhavan},
journal= {arXiv preprint arXiv:2509.13303},
year = {2025}
}