Magnetothermopower and magnetoresistance of single Co-Ni/Cu multilayered nanowires

Böhnert, Tim and Niemann, Anna Corinna and Michel, Ann-Kathrin and Bassler, Svenja and Gooth, Johannes and Tóth, Bence and Neuróhr, Katalin and Péter, László and Bakonyi, Imre and Vega, Victor and Prida, Victor M. and Nielsch, Kornelius (2014) Magnetothermopower and magnetoresistance of single Co-Ni/Cu multilayered nanowires. PHYSICAL REVIEW B CONDENSED MATTER AND MATERIALS PHYSICS, 90. pp. 165416-1. ISSN 1098-0121

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Abstract

The magnetothermopower and the magnetoresistance of single Co Ni/Cu multilayered nanowires with various thicknesses of the Cu spacer are investigated. Both kinds of measure-ment have been performed as a function of temperature (50 K to 325 K) and under applied mag-netic fields perpendicular to the nanowire axis, with magnitudes up to 15 % at room tempera-ture. A linear relation between thermopower S and electrical conductivity σ of the nanowires is found, with the magnetic field as an implicit variable. Combining the linear behavior of the S vs. σ and the Mott formula, the energy derivative of the resistivity has been determined. In order to extract the true nanowire materials parameters from the measured thermopower, a simple model based on the Mott formula is employed to distinguish the individual thermopower contributions of the sample. By assuming that the non-diffusive thermopower contributions of the nanowire can be neglected, it was found that the magnetic field induced changes of thermopower and re-sistivity are equivalent. The main emphasis in the present paper is put on a comparison of the magnetoresistance and magnetothermopower results and it was found that the same correlation is valid between the two sets of data for all samples, irrespective of the relative importance of the giant magnetoresistance or anisotropic magnetoresistance contributions in the various indi-vidual nanowires.

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