Electronic structure and magnetism of layered compounds SrBO2 (B = Ni, Co, Mn): A theoretical investigation

We investigate the electronic structure and magnetic properties of layered compounds SrBO 2 (B = Co, Ni, Mn) based on first principles calculations in the framework of density functional theory with GGA+ U method. We compute the phonon dispersion of these compounds to probe the dynamical stability and find that all the compounds are dynamically stable. SrCoO 2 and SrNiO 2 are G-type antiferromagnetic insulators, and SrMnO 2 is an A-type antiferromagnetic conductor. The electronic configurations of 3d orbitals are (d xz ) 2 (d z 2 ) 2 ( d yz ) 1 (d xy ) 1 (d x 2 - y 2 ) 1 and (d xz ) 2 (dy z ) 2 (d z 2 ) 2 (d xy ) 1 (d x 2 - y 2 ) 1 in SrCoO 2 and SrNiO 2 , respectively. SrCoO 2 shows a Jahn-Teller distortion ( a > b ) because the down-spin Co 3d electron occupies the degenerate (d xz , d yz ) levels. Using Monte Carlo simulations based on the Heisenberg model with exchange parameters obtained from first principles calculations, we obtain the Neel temperatures ( T N ) of SrCoO 2 and SrNiO 2 , which are 249 K and 85 K, respectively.