Multistate magnetoresistance in zigzag-edge trigonal graphene magnetic junctions

Abstract

Using density functional theory combined with nonequilibrium Green’s function method, spin-dependent transport through a zigzag-edge trigonal graphene molecule coupled with two ferromagnets was investigated. The results reveal that due to the intrinsic magnetism of the central graphene nanoflake, four spin configurations of the device can be achieved. By calculating the current–voltage characteristic, a three-state magnetoresistance effect is obtained companied with a large spin filtering efficiency. The intrinsic mechanism is explored as different shifts of the spin-split frontier molecular orbitals depending on the spin configurations of the device. This work indicates an intriguing prospect of graphene nanoflakes in designing novel spintronic devices, such as multistate magnetoresistance devices.