Enhanced Tunnel magnetoresistance in Fe/Mg4Al-Ox/Fe(001) Magnetic Tunnel Junctions

TL;DR

This study demonstrates significantly enhanced tunnel magnetoresistance ratios in Fe/Mg4Al-Ox/Fe(001) magnetic tunnel junctions, showing potential for improved spintronic device performance at room temperature and low temperatures.

Contribution

The paper introduces a new Mg4Al-Ox barrier material that significantly increases TMR ratios compared to traditional MgO barriers in Fe(001) MTJs.

Findings

TMR ratios up to 429% at room temperature

Large TMR oscillation peak-to-valley difference of 125%

Improved barrier interfaces indicated by conductance spectra

Abstract

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 1,034% at 10 K in a Fe/MgAl2O4/Fe(001)-based MTJ prepared using electron-beam evaporation of Mg4Al-Ox. 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 spectra were symmetric with bias polarity, and the spectrum in the parallel magnetization state at low temperature demonstrate significant peaks within broad local minima at |0.2-0.6| V, indicating improved barrier interfaces by the Mg4Al-Ox barrier. This study demonstrates that TMR ratios in Fe(001)-MTJs can still be improved.