In a superconductor that lacks inversion symmetry, the spatial part of the Cooper pair wave function has a reduced symmetry, allowing for the mixing of spin-singlet and spin-triplet Cooper pairing channels and thus providing a pathway to a non-trivial superconducting state. Materials with a non-centrosymmetric crystal structure and with strong spin-orbit coupling are a platform to realize these possibilities. Here, we report the synthesis and characterisation of high quality crystals of Sn4As3, with non-centrosymmetric unit cell (R3m). We have characterised the normal and superconducting state using a range of methods. Angle-resolved photoemission spectroscopy shows a multiband Fermi surface and the presence of two surface states, confirmed by Density-functional theory calculations. Specific heat measurements reveal a superconducting critical temperature of Tc∼1.14 K and an upper critical magnetic field of Hc≳7 mT, which are both confirmed by ultra-low temperature scanning tunneling microscopy and spectroscopy. Scanning tunneling spectroscopy shows a fully formed superconducting gap, consistent with conventional s-wave superconductivity.
@article{arxiv.1912.06625,
title = {Electronic structure and superconductivity of the non-centrosymmetric Sn$_4$As$_3$},
author = {C. A. Marques and M. J. Neat and C. M. Yim and M. D. Watson and L. C. Rhodes and C. Heil and K. S. Pervakov and V. A. Vlasenko and V. M. Pudalov and A. V. Muratov and T. K. Kim and P. Wahl},
journal= {arXiv preprint arXiv:1912.06625},
year = {2020}
}