Abstract
In spintronics, simultaneous realization of high tunneling magnetoresistance and low resistivity in magnetic tunnel junctions (MTJs) is challenging because insulating layers with higher barrier heights generally generate highly spin-polarized currents but increase resistivity. We overcome this trade-off relationship using Brillouin-zone-folded bands at the interfaces in the Fe/spinel ${\mathrm{MgGa}}_{2}{\mathrm{O}}_{4}/\mathrm{Fe}\phantom{\rule{0.16em}{0ex}}\mathrm{MTJ}$. Interfacial resonant states that enhance conductance are formed by folded bands, with Fe--O hybridization playing a key role in the resonant effect intensity at the Fermi level. The electronegativity of cation Ga in spinel oxide ${\mathrm{MgGa}}_{2}{\mathrm{O}}_{4}$ is found to be a crucial physical quantity to control an intensity of the interfacial-resonant effect from the comparative analysis with the ${\mathrm{MgAl}}_{2}{\mathrm{O}}_{4}$-based MTJ.
Highlights
Spin transport, which originates from two-dimensional (2D) electronic structures, has the potential to enhance spinbased phenomena [1]
Spinel bands, which contributes to the spin-dependent tunneling conductance. We demonstrate that both high TMR and low resistance-area product (RA) can be obtained simultaneously through interfacial resonant tunneling in the majority spin caused by the BF effect at the Fe/MgGa2O4(MGO)(001) interface
With parallel magnetization decays more slowly than that with antiparallel magnetization, leading to the increase in the TMR. This is similar to the characteristics of the rock-salt MgO-magnetic tunnel junctions (MTJs)
Summary
Spin transport, which originates from two-dimensional (2D) electronic structures, has the potential to enhance spinbased phenomena [1]. Higher TMR of more than 400% was observed in subsequent experiments This increase was understood to be caused by atomic disordering in the cation sites of MAO, which halves the effective lattice constant and suppresses both the BF effect and the appearance of the minority-spin states [18]. We demonstrate that both high TMR and low RA can be obtained simultaneously through interfacial resonant tunneling in the majority spin caused by the BF effect at the Fe/MgGa2O4(MGO)(001) interface. This interfacial resonant (IR) effect is induced by the folded-band structure at the interface, which enhances the transmittance significantly. There have been no theoretical reports on the spindependent transport properties of MGO-based MTJs to date
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