We study the parent compound of the pyrite-type $Ir_{ x}Ch_{ 2}$ iridium chalcogenide superconductors, $Ir_{ 0.75}Ch_{ 2}$ (or $Ir_{ 3}Ch_{ 8}$). While the lattice structure of the material is rather complicated, we show that the electron physics near the Fermi surface (FS) can be described by a three-band tight-binding model. We find that the material possesses a loop current ground state which is responsible for the highly anisotropic strong diamagnetism observed in experiments. The fluctuations of this loop current state can be a possible pairing mechanism for superconductivity.
Categories: cond-mat.supr-con