Thermoelectric power factor enhancement by spin-polarized currents – a nanowire case study

Niemann, Anna Corinna and Böhnert, Tim and Michel, Ann-Kathrin and Bäßler, Svenja and Gotsmann, Bernd and Neuróhr, Katalin and Tóth, Bence and Péter, László and Bakonyi, Imre and Vega, Victor and Prida, Victor M. and Gooth, Johannes and Nielsch, Kornelius (2016) Thermoelectric power factor enhancement by spin-polarized currents – a nanowire case study. Advanced Electronic Materials, 2 (9). p. 1600058. ISSN 2199-160X

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Abstract

In this work, thermoelectric (TE) measurements have been performed on the workhorses of today’s data storage devices, namely nanostructured materials exhibiting either the giant or the anisotropic magnetoresistance effect (GMR and AMR). In particular, the temperature-dependent (50 K - 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, (rho), as well as the Seebeck coefficient, S, was performed for Co-Ni alloy nanowires exhibiting AMR and Co-Ni/Cu multilayered nanowires exhibiting GMR. 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 were obtained. Furthermore, the TE PF was 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. According to these measurements, 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 hot spots through external magnetic fields.

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