Observation of Ferromagnetic Semiconductor Behaviors from Graphene Doped with Manganese-Oxide By Electrochemical Method

Abstract

Ferromagnetic semiconductors have attracted much attention in the field of spintronic application, because future electronic devices will have a switchable magnetic ordering in semiconductors for exploiting spin rather than charge. The key importance of the magnetic semiconductor is the Curie temperature to maintain the ferromagnetic ordering at room temperature. A high Curie temperature above room temperature has been shown in carbon-based materials. Recently, graphene which is an atomically monolayer graphite, has been an important issue for future spin electronic devices due to the high mobility and superb material properties. Especially, a theoretical result showed that graphene with defects behaves like a diluted magnetic semiconductor (DMS). In general, sp2 hybridized carbon atoms in graphene have an unsaturated dangling bond, which induces various surface modifications. Therefore, doping onto graphene easily leads to modification of the electronic structure, magnetic property, and carrier density. In this work, we report an electrochemical doping of manganese-oxide onto graphene, and also investigate the ferromagnetic semiconductor behavior from the manganese-oxide doped graphene. We have doped a manganese-oxide onto graphene by an electrochemical method. Graphene showed a clear ferromagnetic semiconductor behavior after doping of manganese-oxide. The manganese-oxide doped graphene has a coercive field (Hc) of 232 Oe at 10 K, and has the Curie temperature of 270 K from the temperature-dependent resistivity using transport measurement. The ferromagnetism of manganese-oxide doped graphene attributes to the double-exchange from the coexistence of Mn3+ and Mn4+ on the surface of graphene. In addition, the semiconducting behavior is caused by the formation of manganese-oxide on graphene.