Spin dependent molecular junction with graphene electrodes as a thermoelectric nanodevice

Abstract

Using Green's function method, spin-resolved thermoelectric quantum transport is examined in a molecular junction composed of a phenalene molecule connected to two external graphene leads with and without magnetic exchange potential application on the scattering region. Two different configurations of the system are considered: perpendicular and parallel leads. Theoretical results show that the application of the external exchange potential separates the Seebeck coefficients of different spin states and dramatically increases the coefficients. Furthermore, the temperature gradient between the left and right parts of the system generates a current of nanoAmpere order of magnitude even in the absence of a bias voltage. With the exchange potential, the current is spin-resolved and increased up to 50 times in comparison to the absence of the exchange potential. According to the results, the system acts as a spin filter at some specific chemical potential. Moreover, the current dramatically increases in parallel configuration compared to the perpendicular arrangement. Consequently, the proposed molecular device, with adjustable parameters and a magnificent Seebeck coefficient, can be a promising alternative to ordinary thermoelectric structures in the design of the new generation of thermal spintronic devices.