Spin-dependent thermoelectric properties of a magnetized zigzag graphene nanoribbon

Abstract

Generating spin current by thermal gradient is referred to as Spin caloritronics. Spin caloritronics is an emerging new subfield of condensed matter physics concerned with coupled spin, charge, and energy transport in small structures and devices. In this paper, thermally induced spin transport in a magnetized zigzag graphene nanoribbon is explored. Using non-equilibrium Green’s function (NEGF) method in a tight-binding model, a temperature gradient applied between the left and right nonmagnetic electrodes, as thermal reservoirs in a magnetized zigzag graphene nanoribbon model junction so that the flowing of the up-spin and down-spin currents in the opposite directions can be induced which may be modulated by tuning of the back gate voltage. Furthermore, some thermoelectric properties of the junction, such as the spin-dependent Seebeck effect, electrical conductance, electron thermal conductance, and thermoelectric efficiency (ZT) of the model evaluated. Our calculations for the thermoelectric properties of the magnetized zigzag graphene nanoribbon indicate that for the zigzag edge graphene nanoribbon, the spin-dependent ZT is greater than the ZT of the electric charge. This means that the zigzag edge graphene nanoribbons are appropriate for spin thermal transport applications.

Keywords

• graphene
• spin caloritronics
• spin-dependent seebeck coefficient