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Kondo Effect in Magnetic Tunnel Junctions with an AIOx Tunnel Barrier

Published

Author(s)

Chao Zheng, Robert D. Shull, Andrew P. Chen, Philip Pong

Abstract

The Kondo effect in magnetic tunnel junctions (MTJs) is a result of the spin-exchange interaction between magnetic impurities and the conduction electrons. The presence of the Kondo effect can strongly influence the spin-dependent transport behavior of MTJs. In this work, the temperature dependence of the MTJ resistance (RP) in the parallel (P) magnetization configuration shows an additional contribution to the resistance (R*) below a critical temperature (T = 40 K). The normalized R*(T) curve exhibits a universal scaling behavior and a logarithmic temperature dependence, providing strong evidence for the presence of the Kondo effect in the MTJs. Magnetic impurities formed at the free layer/barrier interface act as scattering centers and thus impede the tunneling of the conduction electrons, leading to an increase of the MTJ resistance. However, the spin-flip scattering associated with the Kondo effect has a nontrivial contribution to the tunneling current in the antiparallel (AP) magnetization configuration, which compensates the reduction of the tunneling current directly caused by the interfacial Kondo scattering, making the R* contribution disappear in the AP magnetization configuration. These results indicate that the manifestation of the Kondo effect is dependent on the magnetization configuration, providing direct experimental evidence of the spin-flip nature of the Kondo effect in the MTJs.
Citation
Physics Letters A

Keywords

Kondo effect, magnetic tunnel junction, magnetic impurities, spin-flip scattering Kondo effect, magnetic tunnel junction, magnetic impurities, spin-flip scattering Kondo effect, magnetic tunnel junction, magnetic impurities, spin-flip scattering Kondo effect, magnetic tunnel junction, magnetic impurities, spin-flip scattering Kondo effect, magnetic tunnel junction, magnetic impurities, spin-flip scattering Kondo effect, magnetic tunnel junction, magnetic impurities, spin-flip scattering

Citation

Zheng, C. , Shull, R. , Chen, A. and Pong, P. (2016), Kondo Effect in Magnetic Tunnel Junctions with an AIOx Tunnel Barrier, Physics Letters A (Accessed May 25, 2024)

Issues

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Created June 16, 2016, Updated October 12, 2021