Distorted magnetic orders and electronic structures for FeSe under pressure

We have studied various magnetic orders and electronic properties as well as pressure-induced effects on FeSe by using density functional theory with combination of Hubbard Model. We find that the Fe spins in striped antiferromagnetic orders with the broken symmetry are more stable in energy than the checkerboard antiferromagnetic ones with tetragonal symmetry. The electronic properties revealed that the enhanced metallic and the suppressed magnetism caused by quantum many-body effects would be the origin for the occurrence of pressure-induced superconductivity in FeSe system, which indicate that the superconductivity of FeSe system showed a closed relationship with the magnetism and its spin fluctuation. These results are useful in understanding the structural, magnetic and electronic properties of FeSe under pressure.

► Fe spins in striped antiferromagnetic order broken symmetry is found ore stable than checkerboard antiferromagnetic one.
► Enhanced metallic and suppressed magnetism is the origin for the occurrence of pressure-induced superconductivity in FeSe.
► Superconductivity of FeSe system showed a closed relationship with the magnetism and its spin fluctuation.