Symphony of Symmetry Selective Resonances in Fe-MgO-ZnO-MgO-Fe

Abstract

We propose the perspective of symmetry-selective resonance of the $\Delta_1$ states in the Fe/MgO/ZnO/MgO/Fe heterostructures, offering a broad landscape to design magnetic tunnel junctions (MTJs) that yield a towering tunnel magnetoresistance (TMR) up to $3.5\times10^4\%$ with the resistance area (RA) product dipping down to a minimum of $0.05~\Omega\cdot\mu \text{m}^2$, while maintaining a nearly perfect (99\%) spin polarization. Our predictions are based on the self-consistent coupling of the non-equilibrium Green's function with density functional theory. We also present the charge current, spin current, and TMR with applied voltage of the Fe/MgO(3-layer)/ZnO(3-layer)/MgO(3-layer)/Fe MTJ, which offers a superior performance triad of TMR ($1.3\times10^4\%$), RA ($0.45~\Omega\cdot\mu \text{m}^2$), and spin polarization (99\%) over a regular Fe/MgO(6-layer)/Fe based MTJ (TMR $\approx 3.4\times10^3\%$, RA $\approx 22~\Omega\cdot\mu \text{m}^2$). We provide a comprehensive insight integrating the transmission eigenchannel, spectral density, and the band structure of the Fe contacts to establish the role of symmetry-selective resonance in the Fe/MgO/ZnO/MgO/Fe MTJ.