  Giant magneto-Seebeck (GMS) effect was observed in Co/Cu/Co and NiFe/Cu/Co
spin valves. Their Seebeck coefficients in parallel state was larger than that
in antiparallel state, and GMS ratio defined as (SAP-SP)/SP could reach -9% in
our case. The GMS originated not only from trivial giant magnetoresistance but
also from spin current generated due to spin polarized thermoelectric
conductivity in ferromagnetic materials and subsequent modulation of the spin
current by spin configurations in spin valves. Simple Mott two-channel model
reproduced a -11% GMS for the Co/Cu/Co spin valves, qualitatively consistent
with our observations. The GMS effect could be applied simultaneously sensing
temperature gradient and magnetic field and also be possibly applied to
determine spin polarization of thermoelectric conductivity and Seebeck
coefficient in ferromagnetic thin films.
