Thermoelectric effect in a graphene sheet connected to ferromagnetic leads

We theoretically investigate the thermoelectric property of a graphene sheet coupled to two ferromagnetic electrodes with noncollinear magnetic moments. By using the nonequilibrium Green's function combining with the tight-binding Hamiltonian, it is demonstrated that the thermopower weakly depends on the polarization strength as well as on magnetic configuration of the leads. On the contrary, the electronic contribution to the thermal conductance is sensitive to both the polarization strength and the relative alignment of magnetization directions. Furthermore, the thermopower shows a linear dependence on temperature and an inverse dependence on the Fermi energy in the graphene, which agrees well the recent experimental measurements.