Spin and Charge Nernst E®ects in Four-Terminal Ferromagnetic Graphene

摘要

The spin and charge Nernst effects in a four-terminal ferromagnetic graphene are theoretically investigated by using the nonequilibrium Greens function method. The results of this study reveal that (1) when the four leads are normal graphene, the pure charge Nernst effect can be obtained under the assistance of magnetic field, (2) when the ferromagnetic graphene leads are in a parallel configuration of the magnetizations, both the spin and charge Nernst effects can be generated simultaneously, it is worth noting that, for the first two cases, the Nernst effect cannot be obtained without the z direction magnetic field, and (3) the pure spin Nernst effect (without charge Nernst effect) emerged only by the temperature difference for the antiparallel configuration. In addition, the magnitude of the spin and charge Nernst coefficients can be tuned by adjusting the strength of magnetic flux and exchange field. All the results indicate that the proposed multi-terminal graphene nanosystem is a promising candidate for spin caloritronics devices.