Effect of a magnetic order on the phase stability of the parent chalcogenide compound FeSe

Abstract

We present results of first-principle calculation of the electronic structure and phase stability of the parent compound of Fe-based superconductors, FeSe, in a magnetically ordered state. In particular, we investigate ferromagnetic (FM) and two different types of antiferromagnetic (AFM) configurations (with magnetic structure vectors (π, 0) and (π, π)). Our results for the total energy exhibit a two-minimum shape for the FM and a standard parabolic-like behavior for the AFM configurations. We find a remarkable reconstruction of the electronic structure near the M point of the Brillouin zone, which is accompanied with a rapid increase in magnetic moment upon expansion of the lattice volume. On that basis we propose that both the anomalous behavior of FeSe upon expansion of the lattice reported for the paramagnetic state [Leonov et al., Phys. Rev. Lett. 115, 106402 (2015)] and that obtained in the present work have a common origin.