Magnetic monolayer superlattices: Another viable class of half-metallic antiferromagnets

We investigate the electronic structures of tetrahedrally coordinated monolayer superlattices (MSLs) to search for half-metallic (HM) antiferromagnetic (AFM) artificial thin films that have no net magnetization, yet 100% spin polarization of the conduction electrons. Using a first-principles density functional method, we find two HM AFM results for CrS/FeS and VS/CoS MSLs, where two constituent magnetic ions have antialigned local moments that cancel exactly by virtue of the integer filling of one spin channel in stoichiometric half-metals. The insertion of ZnS semiconducting layers into MSL structures such as CrS/ZnS/FeS/ZnS do not destroy the overall half-metallicity in MSLs; especially, the HM gap E-g remains unaltered. The exchange splitting is proportional to the local moments but independent of their separation. (c) 2006 Elsevier B.V. All rights reserved.