Magnetothermopower of Co/Cu_1-xNi_x multilayers

We studied the magnetothermopower of Co/Cu1-xNix multilayers (with x=0.37 and 0.42) at various temperatures. Both systems have negative thermopower and the magnitude of the thermopower increases as the magnetic field increases. We found that as the ferromagnetic component of the magnetization becomes larger at lower temperatures, both the magnetothermopower and the magnetoresistance decrease. The inverse relationship between the thermopower and the resistance, when the field H varies, holds well at different temperatures. We interpret the results in terms of the two-current model, with an emphasis on the spin-split density of states.