  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.
