In the recent work by Song et al. [Science 332, 1410 (2011)], the scanning tunneling spectroscopy experiment in the stoichiometric FeSe reveals evidence for nodal superconductivity and strong anisotropy. The nodal structure can be explained with the extended s-wave pairing structure with the mixture of the sx2+y2 and sx2y2 pairing symmetries. We calculate the anisotropic vortex structure by using the self-consistent Bogoliubov-de Gennes mean-field theory. In considering the absence of magnetic ordering in the FeSe at the ambient pressure, orbital ordering is introduced, which breaks the C4 lattice symmetry down to C2, to explain the anisotropy in the vortex tunneling spectra.
@article{arxiv.1109.6116,
title = {Anisotropic vortex lattice structures in the FeSe superconductor},
author = {Hsiang-Hsuan Hung and Can-Li Song and Xi Chen and Xucun Ma and Qi-kun Xue and Congjun Wu},
journal= {arXiv preprint arXiv:1109.6116},
year = {2012}
}