We have theoretically explored the intrinsic spin Hall effect (SHE) in the iron-based superconductor family with a variety of materials. The study is motivated by an observation that, in addition to an appreciable spin-orbit coupling in the Fe 3d states, a character of the band structure in which Dirac cones appear below the Fermi energy may play a crucial role in producing a large SHE. Our investigation does indeed predict a substantially large spin Hall conductivity in the heavily hole-doped regime such as KFe2As2. The magnitude of the SHE has turned out to be comparable with that for Pt despite a relatively small spin-orbit coupling, which we identify to come from a huge contribution from the gap opening induced by the spin-orbit coupling at the Dirac point, which can become close to the Fermi energy for the heavy hole doping.
@article{arxiv.1107.0122,
title = {Spin Hall effect in iron-based superconductors: A Dirac-point effect},
author = {Sudhakar Pandey and Hiroshi Kontani and Dai S. Hirashima and Ryotaro Arita and Hideo Aoki},
journal= {arXiv preprint arXiv:1107.0122},
year = {2012}
}