Electronic structure and magnetic couplings in iron–cobalt borides compounds

Abstract In this paper, we report on calculations of the electronic structure and the magnetic coupling in Fe1−xCoxB and (Fe1−xCox)2B iron–cobalt borides. In Fe1−xCoxB, the atomic magnetic moments decrease versus x the Co concentration and a ferromagnetic–nonmagnetic phase transition occurs at x ∼ 0.9 . For this series, our calculations show the presence of a small magnetic polarization on Co. For both series of borides, core hyperfine fields on atoms were also calculated. The Fe and Co spin magnetic moments μspin and core hyperfine fields Bhfcore exhibit similar concentration dependencies so that the ratio Bhfcore/μspin reveals not sensitive to the Co concentration.