Enhanced tunnel magnetoresistance in Fe/Mg4Al-Ox/Fe(001) magnetic tunnel junctions

Spinel MgAl2O4 and family oxides are emerging barrier materials useful for magnetic tunnel junctions (MTJs). We report large tunnel magnetoresistance (TMR) ratios up to 429% at room temperature (RT) and 1034% at 10 K in a Fe/Mg-rich spinel/Fe(001) MTJ prepared using electron-beam evaporation of Mg4Al-O-x. Resistance oscillations with a MTJ barrier thickness of 0.3 nm were significantly enhanced compared to those of a Fe/MgO/Fe(001) MTJ, resulting in a large TMR oscillation peak-to-valley difference of 125% at RT. The differential conductance (dI/dV) spectra were symmetric with bias polarity, and the spectrum in the parallel magnetization state at low temperature demonstrates significant peaks within broad local minima at |V| = 0.2-0.6 V, indicating improved barrier interfaces by the Mg4Al-O-x barrier. This study demonstrates that TMR ratios in Fe(001)-MTJs can still be improved.

Automated summary

This article reports large TMR ratios in Fe/Mg-rich spinel/Fe(001) MTJs prepared using Mg4Al-O-x barrier, reaching 429% at room temperature and 1034% at 10 K. The resistance oscillations, significantly enhanced compared to Fe/MgO/Fe(001) MTJs, resulted in a large peak-to-valley difference of 125% at room temperature. Improved barrier interfaces were demonstrated by the Mg4Al-O-x barrier.