Tight binding model for magneto-crystalline anisotropy in MnBi

With the help of density functional theory based first-principles calculations and a tight- binding model Hamiltonian we studied the origin of magnetic properties in the ferromagnet MnBi. The model Hamiltonian show that direct electron hopping within the nearest and next nearest Bi-p orbitals are responsible for the large band dispersions. The Mn-d bands are fairly narrow with band widths < 2 eV. A Stoner model with spin-orbit coupling leads to the observed negative MAE with this Hamiltonian.