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

TL;DR

This study investigates the magnetothermopower and magnetoresistance of single Co-Ni/Cu multilayered nanowires, revealing a linear relation between thermopower and conductivity and establishing a correlation between magnetic field effects on both properties across various samples.

Contribution

It introduces a simple model based on the Mott formula to distinguish thermopower contributions and compares magnetothermopower with magnetoresistance, demonstrating their correlated behavior in nanowires.

Findings

Linear S vs. σ relation with magnetic field as an implicit variable

Magnetic field induced changes in thermopower and resistivity are equivalent

Consistent correlation between magnetothermopower and magnetoresistance across samples

Abstract

The magnetothermopower and the magnetoresistance of single Co Ni/Cu multilayered nan-owires with various thicknesses of the Cu spacer are investigated. Both kinds of measurement have been performed as a function of temperature (50 K to 325 K) and under applied magnetic fields perpendicular to the nanowire axis, with magnitudes up to 15 % at room temperature. A linear relation between thermopower S and electrical conductivity {\sigma} of the nanowires is found, with the magnetic field as an implicit variable. Combining the linear behavior of the S vs. {\sigma} 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 resistivity are equivalent. The emphasis in the present paper is on the comparison of the magnetoresistance and magnetothermopower results and it is 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 individual nanowires.