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Spin-dependent Seebeck coefficients of Ni80Fe20 and Co in nanopillar spin valves

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posted on 11.10.2018, 14:35 by Fasil DejeneFasil Dejene, J. Flipse, B.J. van Wees
We have experimentally determined the spin-dependent Seebeck coefficient of permalloy (Ni80Fe20) and cobalt (Co) using nanopillar spin valve devices, a stack of two ferromagnetic layers separated by a nonmagnetic layer. The devices were specifically designed to separate heat-related effects from charge-related effects. A heat current, with no accompanying charge current, through the nanopillar spin valve leads to a thermovoltage proportional to the spin-dependent Seebeck coefficient SS = S↑ − S↓ of the ferromagnet, where S↑ and S↓ are the Seebeck coefficient for spin-up and spin-down electrons. By using a three-dimensional finite-element model based on spin-dependent thermoelectric theory, whose input material parameters were measured in separate devices, we were able to accurately determine a spin-dependent Seebeck coefficient of −1.8 μV K−1 and −4.5 μV K−1 for cobalt and permalloy, respectively, corresponding to a Seebeck coefficient polarization PS = SS /SF of 0.08 and 0.25, where SF is the Seebeck coefficient of the ferromagnet. The results are in agreement with earlier theoretical work in Co/Cu multilayers and spin-dependent Seebeck and spin-dependent Peltier measurements in Ni80Fe20/Cu spin valve structures.

History

School

  • Science

Department

  • Physics

Published in

Physical Review B

Volume

86

Issue

2

Citation

DEJENE, F.K., FLIPSE, J. and VAN WEES, B.J., 2012. Spin-dependent Seebeck coefficients of Ni80Fe20 and Co in nanopillar spin valves. Physical Review B, 86 (2), 024436.

Publisher

© American Physical Society

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2012

Notes

This paper was published in the journal Physical Review B and the definitive published version is available at https://doi.org/10.1103/PhysRevB.86.024436.

ISSN

2469-9950

eISSN

2469-9969

Language

en

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