Room temperature spin Kondo effect and intermixing in Co/Cu non-local spin valves

Watts, JD, Jeong, JS, O'Brien, L ORCID: 0000-0002-0136-8603, Mkhoyan, KA, Crowell, PA and Leighton, C
(2017) Room temperature spin Kondo effect and intermixing in Co/Cu non-local spin valves. APPLIED PHYSICS LETTERS, 110 (22).

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The anomalous low temperature suppression of the spin accumulation signalDRNLin non-localspin valves (NLSVs) based on common ferromagnet (FM)/normal metal (N) pairings has recentlybeen shown to result from a manifestation of the Kondo effect. Local magnetic moments in the Ndue to even minor levels of FM/N interdiffusion depolarize the injected spin current, suppressingthe effective spin polarization around and below the Kondo temperatureTK. Previous studies havefocused on FM/N combinations that happen to have lowTKso that Kondo effects occur only wellbelow 300 K. Here, we study NLSVs based on Co/Cu, a materials combination that is not onlytechnologically relevant but also has a highTK, up to 500 K. Despite the negligibleequilibriumsol-ubility of Co in Cu, we find clear Kondo effects in bothDRNLand Cu resistivity, due to Co/Cuintermixing that we probeviaquantitative transmission electron microscopy. Most significantly,under certain conditions the spin Kondo effect suppresses the injected spin polarizationeven atroom temperature, with important technological implications. Studies as a function of the Cu thick-ness and annealing temperature reveal complex trends in interdiffusion lengths and Kondo effects,which we interpret in terms of the interplay between diffusion kinetics and thermodynamics, aswell as the thickness dependence of the Kondo effect.

Item Type: Article
Depositing User: Symplectic Admin
Date Deposited: 03 Jul 2017 10:19
Last Modified: 25 Nov 2021 23:11
DOI: 10.1063/1.4984896
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