Through first-principles calculations, we investigate the quantum-well resonance enhanced tunneling magnetoresistance (TMR) effect in magnetic tunnel junctions (MTJs) with interface oxidation, specifically examining Al/Fe/FeO/MgO/Fe and Ag/Al/Fe/FeO/MgO/Fe MTJs. Our study reveals that the Fe layer situated between Al and FeO exhibits spin-polarized quantum-well resonance states, arising from the combination between the partial confinement of ${\mathrm{\Delta }}_1$ electron at the Al/Fe interface and the full confinement at the FeO/MgO boundary. By changing the quantum-well thickness (controlled by Fe layer thickness) or interfacial phase shift (modulated via Al layer thickness), the quantum-well level of one spin-polarized state can be tuned near the Fermi level, leading to a high conductance in parallel state. This mechanism greatly enhances the optimistic TMR ratio from 400% in Fe/FeO/MgO/Fe MTJ to 3500% in Al/Fe/FeO/MgO/Fe MTJ and 9600% in Ag/Al/Fe/FeO/MgO/Fe MTJ. This study demonstrates that quantum-well resonance remains functionally robust under the interface oxidation—an advancement for practical spintronics applications.

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• Tunneling magnetoresistance
• Magnetic tunnel junctions
• Quantum wells
• First-principles calculations