▎ 摘　　要

Graphene is predicted to hold a promising use for developing future miniaturized electronic devices. However, the magnetic transport properties based on the armchair-edged graphene nanoribbons (AGNRs) is less studied in currently existing work. So in this work the special chemical modified nanoribbons based on the edge of the AGNR bridged by the transition metal Mn atom and passivated subsequently by two F atoms or two H atoms (AGNR-Mn-F-2 or AGNR-Mn-H-2) are proposed theoretically. Our calculations from first-principle method based on the spin-polarized density functional theory combined with the non-equilibrium Green's function technique show that the heterojunction F-2-AGNR-Mn-H-2 consisting of such two types of nanoribbons possesses the excellent magnetic device features, namely, the spin polarization is able to reach almost 100% in a very large bias region, and under P magnetic configuration (the external magnetic fields applied perpendicularly to two electrodes are set to point to the same direction), the single spin filtering effects can be realized, while under the AP configuration (the external magnetic fields applied perpendicularly to two electrodes are set to point to the opposite directions), the dual spin filtering effects can be realized. It is also found that such a heterojunction features dual diode-like effect, and its rectification ratio is up to be 10(8). Additionally, changing the direction of switching magnetic field, namely, changing the magnetic configurations from one kind of case to another, would lead to an obvious spin valve effect, and the giant magnetoresistace approaches to 10(8)%. These findings suggest that the excellent spin polarization, dual diode-like effect, and giant magnetoresistace effect can be realized simultaneously for this heterojunction, therefore, it holds good promise in developing spintronic devices.