Title: Thermoelectric power factor enhancement by spin-polarized currents - a nanowire case study,
Abstract: Thermoelectric (TE) measurements have been performed on the workhorses of
today's data storage devices, exhibiting either the giant or the anisotropic
magnetoresistance effect (GMR and AMR). The temperature-dependent (50-300 K)
and magnetic field-dependent (up to 1 T) TE power factor (PF) has been
determined for several Co-Ni alloy nanowires with varying Co:Ni ratios as well
as for Co-Ni/Cu multilayered nanowires with various Cu layer thicknesses, which
were all synthesized via a template-assisted electrodeposition process. A
systematic investigation of the resistivity, as well as the Seebeck
coefficient, is performed for Co-Ni alloy nanowires and Co-Ni/Cu multilayered
nanowires. At room temperature, measured values of TE PFs up to 3.6 mWK-2m-1
for AMR samples and 2.0 mWK-2m-1 for GMR nanowires are obtained. Furthermore,
the TE PF is found to increase by up to 13.1 % for AMR Co-Ni alloy nanowires
and by up to 52 % for GMR Co-Ni/Cu samples in an external applied magnetic
field. The magnetic nanowires exhibit TE PFs that are of the same order of
magnitude as TE PFs of Bi-Sb-Se-Te based thermoelectric materials and,
additionally, give the opportunity to adjust the TE power output to changing
loads and hotspots through external magnetic fields.