Giant magnetoresistance and dual spin filtering effect in ferromagnetic 6,6,12/γ-graphyne zigzag nanoribbon lateral heterojunction

Based on non-equilibrium Green's function combined with density functional theory (NEGF-DFT), we investigate the spin dependent transport in the ferromagnetic 6,6,12/γ-graphyne zigzag nanoribbon (GYZNR) heterojunction under different magnetic configurations. It is found that, at low bias ([-0.05, 0.1] V), the junction presents metallic transport with negligible spin polarization in parallel configuration (PC) while it behaves as an insulator in anti-parallel configuration (APC), which results in giant magnetoresistance. Interestingly, when we increase the bias voltage beyond [-0.05, 0.1] V, dual spin filtering characterized by electron transport of different spin channel under different polarity of bias is observed in APC but not in PC. All these findings are understood from the symmetry matching of wave functions in two nanoribbons at equilibrium or finite bias. Furthermore, dual spin filtering can also be achieved in PC by applying a gate voltage on the central interface region, which arises from the shift of different single spin channel of the central gate region into the bias window at the different polarity of the gate voltage. Thus, our work demonstrates the great potential of 6,6,12/γ-GYZNR heterojunction as a multi-functional device and its great perspectives in carbon based nanoelectronics and spintronics.