Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 108: Spin-Dependent Transport Phenomena II (organized by MA)

TT 108.11: Talk

Thursday, March 19, 2015, 17:45–18:00, H 0112

Tunable Thermoelectric Power Factors of Magnetoresistive Nanowires — •Anna Niemann¹, Tim Böhnert¹, Ann-Kathrin Michel¹, Svenja Bäßler¹, Johannes Gooth¹, Bence G. Tóth², Katalin Neuróhr², László Péter², Imre Bakonyi², Victor Vega³, Victor M. Prida³, and Kornelius Nielsch¹ — ¹Universität Hamburg, Hamburg, Germany — ²Hungarian Academy of Sciences, Budapest, Hungary — ³Universidad de Oviedo, Oviedo, Spain

We present spin-caloric transport in single Co-Ni alloy and multilayered Co-Ni/Cu nanowires, including magnetoresistance (MR) and magneto-thermopower (MTP) measurements. Co-Ni alloy nanowires show anisotropic MR while multilayered nanowires show predominant giant MR. MTP and MR are studied in a temperature range between 50 K and 325 K leading to effect sizes up to 6 % for Co-Ni alloy samples and up to 15 % for multilayered samples at room temperature. While the thermopower describes a material’s ability to convert temperature gradients into electrical voltage, thermoelectric power factors (PFs) give a measure of the electrical power generated from thermoelectric effects. The PFs of our nanowires can compete with common thermoelectric bulk materials like Bi₂Te₃. Additionally, a magnetic field-dependence of the nanowires’ PFs can be observed. PFs of Co-Ni nanowires increase by 24 % in an external magnetic field, while PFs of multilayered nanowires can be increased by up to 40 %. This magnetic field dependence opens interesting opportunities to tune electrical power output according to applicational needs.