Breakdown of half-metallic ferromagnetism in zinc-blende II-V compounds

We investigated the electronic and magnetic properties of a series of zinc-blend II-V compounds by carrying out density-functional-theory calculations including spin-orbit couplings. Contrary to the case of CaN and CaP, the half-metallic characteristics of the II-V compounds such as CaSb and CaBi were found to be destroyed. Our analysis of the valence band structures of CaAs, CaSb, and CaBi revealed a critical role of the spin-orbit coupling interactions on the exchange-split band structure, thereby leading to breakdown of the half-metallic ferromagnetism for the systems with heavier group V elements in the zinc-blend II-V compounds.