Half-metallic ferromagnetism in tetrahedrally coordinated compounds MGe (M = Ca, Sr and Ba): Ab initio calculations

Using the full potential linearized augment plane wave method with the generalized gradient approximation and the modified Becke and Johnson potential as exchange correlation potential, the half-metallicity, electronic structure and heat of formation for hypothetical compounds MGe (M = Ca, Sr and Ba) with ZB and WZ structure are investigated. Calculations show that tetrahedral coordinated MGe alloys are half-metallicity, with magnetic moment of 2.00 (4.00) μB per cell for the ZB (WZ) structure. Magnetic moments are mainly from Ge-p states, where in p–d hybridization mechanism plays crucial role in forming the half-metallicity. The ferromagnetic ground states, larger half-metallic gaps, negative cohesive energy and heat of formation indicate tetrahedral coordinated MGe (M = Ca, Sr and Ba) compounds would be useful in spintronics.