Ab initio study on the role of the crystalline symmetry in the stabilization of the magnetic order in Al-doped SnS

Abstract

We use firstprinciples calculations to study the electronic and magneticproperties of undoped and Al-doped SnS and their dependence withspace-group symmetry. The formation of a magnetic moment due to animpurity element was analyzed by substitutional doping inPnma(62)-SnS and C2mb(39)-SnS symmetries. The holes introduced bycation Al-doping leads to the formation of a magnetic moment of 1.0 μB /impurity, and a half-metallic behavior. Orbital configurationswith local magnetic moments are established due to stronghybridization between {s;p} -Al orbitals and {s;p} -S orbitals. Thecollective magnetic order was analyzed by the effectiveexchange-coupling parameters between Al atoms at different atomiccationic sites, and different hole concentrations. These resultsindicate that the stabilization of the magnetic order presents astrong dependence with the spatial arrangement and the exchangepathways. For nearby dopants, and at the same holes concentration,both the Pnma and the C2mb symmetries present an AFM behavior. Thiscollective magnetic order changes to a ferromagnetic coupling for thecase in which the dopants are further away or when there is a higherholes concentration. The origin of such magnetic ordering can beunderstood based on the competition between hole-mediatedsuperexchange and double exchange mechanisms. Our predictive resultsoffer the possibility to distinguish between holes doping effect andthe role of symmetry in the coordination of the dopant, of greatimportance to the understanding of the origin of defect-inducedmagnetism.p { margin-bottom: 0.1in; line-height: 115%; }