Zero-bias conductance peak in detached flakes of superconducting   2H-TaS$_2$ probed by scanning tunneling spectroscopy
  We report an anomalous tunneling conductance with a zero bias peak in flakes of superconducting 2H-TaS$_2$ detached through mechanical exfoliation. To explain the observed phenomenon, we construct a minimal model for a single unit cell layer of superconducting 2H-TaS$_2$ with a simplified 2D Fermi surface and sign-changing Cooper pair wavefunction induced by Coulomb repulsion. Superconductivity is induced in the central $\Gamma$ pocket, where it becomes nodal. We show that weak scattering at the nodal Fermi surface, produced by non-perturbative 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 a few atom thick crystals could drive a crossover from conventional to sign changing pairing in the superconductor 2H-TaS$_2$. 
J. A. Galvis, L. Chirolli, I. Guillamon, S. Vieira, E.   Navarro-Moratalla, E. Coronado, H. Suderow, F. Guinea
cond-mat.supr-con