1211.0923 (H. Sims et al.)

Theoretical investigation into the possibility of very large moments in
Fe16N2    [PDF]

H. Sims, W. H. Butler, M. Richter, K. Koepernik, E. Sasioglu, C. Friedrich, S. Blügel

We examine the mystery of the disputed high-magnetization \alpha"-Fe16N2 phase, employing the Heyd-Scuseria-Ernzerhof screened hybrid functional method, perturbative many-body corrections through the GW approximation, and onsite Coulomb correlations through the GGA+U method. We present a first-principles computation of the effective on-site Coulomb interaction (Hubbard U) between localized 3d electrons employing the constrained random-phase approximation (cRPA), finding only somewhat stronger on-site correlations than in bcc Fe. We find that the hybrid functional method, the GW approximation, and the GGA+U method (using parameters computed from cRPA) yield an average spin moment of 2.9, 2.6 - 2.7, and 2.7 \mu_B per Fe, respectively.

View original: http://arxiv.org/abs/1211.0923