Giant decreasing of spin current in a single molecular junction with twisted zigzag graphene nanoribbon electrodes

Molecular spintronics is a new and emergent sub-area of spintronics that has the potential use in future information storage, magnetic sensing and quantum computing. We investigate the spin transport properties of a single benzene molecule connected to zigzag graphene nanoribbons (ZGNRs) by using a self-consistent ab initio approach which combines the non-equilibrium Green's function (NEGF) formalism with density functional theory (DFT). The spin-resolved current-voltage characteristics of the single benzene molecule at finite biases are different while the left and right zigzag graphene electrodes with the parallel (P) and anti-parallel (AP) magnetism configurations. The perfect (100%) spin polarization in a large bias region can be realized with both P and AP magnetism configuration. However, the spin-resolved rectifications are only found with AP magnetism configuration. More importantly, both of the α-spin and β-spin currents would drop remarkably when one ZGNR electrode is twisted. Especially the α-spin currents with P magnetism configuration will decrease by up to 8 orders of magnitude when the twisted angle reaches 90°. The above results demonstrate that this junction holds promise in the design of a high-performance multifunctional single-molecule spintronic device.