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We theoretically analyze contributions from the Kondo effect to the spin polarization and spin diffusion length in all-metal nonlocal spin valves. Interdiffusion of ferromagnetic atoms into the normal metal layer creates a region in which Kondo physics plays a significant role, giving discrepancies between experiment and existing theory. We start from a simple model and construct a modified spin drift-diffusion equation which clearly demonstrates how the Kondo physics not only suppresses the electrical conductivity but even more strongly reduces the spin diffusion length. We also present an explicit expression for the suppression of spin polarization due to Kondo physics in an illustrative regime. We compare this theory to previous experimental data to extract an estimate of the Elliot-Yafet probability for Kondo spin flip scattering of 0.7±0.4, in good agreement with the value of 2/3 derived in the original theory of Kondo.
Bibliographical noteFunding Information:
The authors acknowledge P. Haney and O. Gomonay for critical reading of the manuscript. K.W.K. was supported by the Cooperative Research Agreement between the University of Maryland and the National Institute of Standards and Technology, Center for Nanoscale Science and Technology (70NANB10H193), through the University of Maryland. K.W.K also acknowledges support by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2016R1A6A3A03008831), Alexander von Humboldt Foundation, the ERC Synergy Grant SC2 (No. 610115), and the Transregional Collaborative Research Center (SFB/TRR) 173 SPIN+X. Work at the University of Minnesota was funded by Seagate Technology Inc., the University of Minnesota (UMN) NSF MRSEC under Awards No. DMR-1420013, and No. DMR-1507048. L.O'B. acknowledges a Marie Curie International Outgoing Fellowship within European Community Seventh Framework Programme (Project No. 299376).
How much support was provided by MRSEC?
Reporting period for MRSEC
- Period 3
PubMed: MeSH publication types
- Journal Article