6533b82efe1ef96bd12945ac

RESEARCH PRODUCT

Zero-bias conductance peak in detached flakes of superconducting 2H-TaS2probed by scanning tunneling spectroscopy

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We report an anomalous tunneling conductance with a zero-bias peak in flakes of superconducting 2$H$-${\mathrm{TaS}}_{2}$ detached through mechanical exfoliation. To explain the observed phenomenon, we construct a minimal model for a single unit cell layer of superconducting 2$H$-${\mathrm{TaS}}_{2}$ with a simplified two-dimensional Fermi surface and a sign-changing Cooper-pair wave function induced by Coulomb repulsion. Superconductivity is induced in the central $\ensuremath{\Gamma}$ pocket, where it becomes nodal. We show that weak scattering at the nodal Fermi surface, produced by nonperturbative coupling between tip and sample, gives Andreev states that lead to a zero-bias peak in the tunneling conductance. We suggest that reducing dimensionality down to crystals a few atoms thick could drive a crossover from conventional to sign-changing pairing in the superconductor 2$H$-${\mathrm{TaS}}_{2}$.