Magneto-thermoelectric figure of merit of Co/Cu multilayers

The switching of the magnetization configurations of giant magnetoresistance multilayer stacks not only changes the electric and thermal conductivities, but also the thermopower. We study the magnetotransport and the magneto-thermoelectric properties of Co/Cu multilayer devices in a lateral thermal gradient. We derive values of the Seebeck coefficient, the thermoelectric figure of merit, and the thermoelectric power factor. The Seebeck coefficient reaches values up to -18 microvolt/K at room temperature and shows a magnetic field dependence up to 28.6 % upon spin reversal. In combination with thermal conductivity data of the same Co/Cu stack, we find a spin dependence of the thermoelectric figure of merit of up to 65 %. Furthermore, a spin dependence of the power factor of up to 110 % is derived.