Effect of Fe Doping and Point Defects (VO and VSn) on the Magnetic Properties of SnO2

Abstract

We investigated the effects of Fe doping and point defects (oxygen and tin vacancies, VO and VSn, respectively) on the ferromagnetism of SnO2 through first-principles calculations by using generalized gradient approximation + U under density functional theory. Calculation results show that Fe-doped SnO2 with VO or VSn exhibit long-range ordered ferromagnetism and Curie temperature above room temperature. The system has different magnetic properties with different doping modes, which are beneficial to the magnetic adjustment of dilute magnetic semiconductor (DMS). The double-exchange effects among the electrons of O–2p and Fe–3d states are the origin of ferromagnetism in Sn15FeO31. Similarly, ferromagnetism in Sn14FeO32 is derived from the double-exchange effects among the electrons of O–2p and Fe–3d states. These effects are produced by hole carriers after complexes form by Fe doping and VO or VSn. Simultaneously, Sn14FeO32 shows a half-metallic behavior, thus resulting in 100% conduction hole polarizability, which is highly beneficial to DMSs as a hole-injection source. Moreover, results also show that the decreased distance between Fe and vacancies (VO or VSn) lowers formation energy and thus increases the system stability.