Spin transport properties in lower n-acene-graphene nanojunctions.

A series of n-acene-graphene (n = 3, 4, 5, 6) devices, in which n-acene molecules are sandwiched between two zigzag graphene nanoribbon (ZGNR) electrodes, are modeled through the spin polarized density functional theory combined with the non-equilibrium Green's function technique. Our theoretical results show that for n-acene molecules ranging from anthracene to hexacene, the spin-polarized electronic states near the Fermi level can be induced by the spin-polarized ZGNR electrodes, which strengthen gradually to facilitate the electronic transport. A nearly 100% spin filtering ratio and a dual-orientation spin-rectifying effect are observed in a wide range of bias voltage. Importantly, an over 8000% giant magnetoresistance is obtained in the low bias range from -0.1 V to +0.1 V. Moreover, negative differential resistance behaviors are detected in these devices. The potential mechanisms of these intriguing phenomena are proposed and these findings would be instructive for the design and synthesis of high-performance graphene-based spin-related devices.