Kondo effect in magnetic tunnel junctions with an AlOx tunnel barrier

• The presence of the Kondo effect in a magnetic tunnel junction (MTJ) is observed.
• A logarithmic temperature-resistance dependence proves the presence of the Kondo effect.
• Interfacial magnetic impurities act as scattering centers and impede the current.
• The manifestation of the Kondo effect relies on the magnetization configuration.
• Spin-flip scattering nontrivially contributes to the current in the antiparallel state.

The influence of the magnetization configuration on the Kondo effect in a magnetic tunnel junction is investigated. In the parallel configuration, an additional resistance contribution (R⁎R⁎) below 40 K exhibits a logarithmic temperature dependence, indicating the presence of the Kondo effect. However, in the anti-parallel configuration, the Kondo-effect-associated spin-flip scattering has a nontrivial contribution to the tunneling current, which compensates the reduction of the current directly caused by Kondo scattering, making R⁎R⁎ disappear. These results indicate that suppression and restoration of the Kondo effect can be experimentally achieved by altering the magnetization configuration, enhancing our understanding of the role of the Kondo effect in spin-dependent transport.