Observation of spin-polarized surface states in the nodal-line semimetal SnTaS2

The superconductor SnTaS$_{2}$ is theoretically predicted to be an intriguing\ntopological nodal line semimetal without consideration of spin-orbit coupling.\nBy carrying out angle-resolved photoemission (ARPES) and spin-resolved ARPES\nmeasurements combined with band structure calculations, we have provided a\ncomplete picture of the electronic structure and spin polarization property for\nthe prominent surface states of SnTaS$_{2}$. The low-energy electronic states\nare dominated by surface states; two of them are from the S-terminated surface,\nwhile four of them are from the Sn-terminated surface. These give rise to\ninteresting Fermi surface topology of SnTaS$_{2}$: three pockets located at\n$\\bar\\Gamma$, $\\bar{M}$ and $\\bar{K}$ for the S-terminated surface and two\npockets surrounding $\\bar\\Gamma$ and $\\bar{K}$ for the Sn-terminated surface.\nWe further reveal that two surface states that cross the Fermi level are\nspin-polarized. Since SnTaS$_{2}$ is also a superconductor, our observations\nindicate that it may provide a new platform to explore topological\nsuperconductivity and other exotic properties.\n