Abstract
We have studied electronic and magnetic structures of FeSe by performing the first-principles electronic structure calculations. The ground state of the Fe-vacancies ordered FeSe is found to be a quasi-two-dimensional blocked checkerboard antiferromagnetic (AFM) semiconductor with an energy gap of 594 meV and a large ordering magnetic moment of 3.37 for each Fe atom, in excellent agreement with the neutron-scattering measurement. The underlying mechanism is the chemical-bonding-driven tetramer lattice distortion. FeSe with finite is a doped AFM semiconductor with low conducting carrier concentration, which is approximately proportional to the excess potassium content, consistent qualitatively with the infrared observation. Our study reveals the importance of the interplay between antiferromagnetism and superconductivity in these materials. This suggests that FeSe, instead of KFeSe, should be regarded as a parent compound from which the superconductivity emerges upon electron or hole doping.
- Received 2 March 2011
DOI:https://doi.org/10.1103/PhysRevB.83.233205
©2011 American Physical Society