Half metallic antiferromagnetic behavior in doped TiO_2 rutile with double impurities (Os, Mo) from ab initio calculations

摘要

Electronic and magnetic calculations were based on density functional theory within the generalized gradient approximation for Ⅱ-Ⅵ compound semiconductor TiO_2 doped with single impurity Os and Mo; these compounds are half-metallic ferromagnets in their ground state with a total magnetic moment of 2μ_B for both systems. Then, doping TiO_2 with double impurities (Os, Mo) was performed. As a result Ti_(1-2x)Os_xMo_xO_2 with x = 0.065 is a half-metallic antiferromagnet with 100% spin polarization of the conduction electrons crossing the Fermi level, without showing a net magnetization. Moreover, the Ti_(14)OsMoO_(32) compound is stable energetically than Ti_(1-x)Mo_xO_2 and Ti_(1-x)Os_xO_2. The antiferromagnetic interaction in the Ti_(1-2x)Os_xMo_xO_2 system is attributed to the double exchange mechanism, and the latter could also be the origin of their half-metallic behavior.