Electronic vortex structure of Fe-based superconductors: Application to LiFeAs

The understanding of the microscopic origin of electron pairing in strongly correlated electron systems remains an ultimate goal in the field of unconventional superconductivity. Detailed tunneling spectroscopy of vortex core states can provide important insight to the momentum structure of the superconducting order parameter, which is closely related to the nature of the electron pairing. The authors performed a fully self-consistent real-space BdG study of vortex core states in five-orbital models relevant to Fe-based superconductors. The superconducting order was stabilized by spin fluctuation-derived pairing vertices generating an ${s}_{\ifmmode\pm\else\textpm\fi{}}$-wave gap structure. By application to LiFeAs, they find striking agreement with STS measurements by Hanaguri $e\phantom{\rule{0}{0ex}}t$ $a\phantom{\rule{0}{0ex}}l$. on this compound. In particular, the details of the energy dependence and the spatial structure seems in almost quantitative agreement without any tuning parameters. From this fact they conclude that their model provides a reasonable description of LiFeAs, without the necessity to invoke more exotic paring states of this material.