Large inverse tunneling magnetoresistance in Co$_2$Cr$_{0.6}$Fe$_{0.4}$Al/MgO/CoFe magnetic tunnel junctions

TL;DR

This study reports the fabrication of magnetic tunnel junctions with Co2Cr0.6Fe0.4Al/MgO/CoFe layers that exhibit a large inverse tunneling magnetoresistance effect, stable across temperatures, with unique voltage dependence features.

Contribution

It demonstrates the realization of large inverse TMR in Co-based full-Heusler alloy junctions at room temperature and low temperature, with detailed voltage dependence analysis.

Findings

Inverse TMR of up to -66% at room temperature

Maximum inverse TMR of -84% at 20 K

Unusual symmetric peaks in TMR at ±600 mV voltage bias

Abstract

Magnetic tunnel junctions with the layer sequence Co$_2$Cr$_{0.6}$Fe$_{0.4}$Al/MgO/CoFe were fabricated by magnetron sputtering at room temperature (RT). The samples exhibit a large inverse tunneling magnetoresistance (TMR) effect of up to -66% at RT. The largest value of -84% at 20 K reflects a rather weak influence of temperature. The dependence on the voltage drop shows an unusual behavior with two almost symmetric peaks at $\pm600$ mV with large inverse TMR ratios and small positive values around zero bias.