Epitaxial Co2Cr0.6Fe0.4Al thin films and magnetic tunneling junctions

TL;DR

This study reports the fabrication and characterization of epitaxial Co2Cr0.6Fe0.4Al thin films and magnetic tunneling junctions, revealing a significant spin polarization and the influence of annealing on tunneling magnetoresistance.

Contribution

It demonstrates the successful growth of epitaxial Co2Cr0.6Fe0.4Al films with high order and investigates their magnetic tunneling properties, including the effects of annealing.

Findings

Spin polarization of 54% at 4K for Co2Cr0.6Fe0.4Al.

Tunneling magnetoresistance depends on annealing temperature.

Epitaxial growth achieved with small disorder on Co sites.

Abstract

Epitaxial thin films of the theoretically predicted half metal Co2Cr0.6Fe0.4Al were deposited by dc magnetron sputtering on different substrates and buffer layers. The samples were characterized by x-ray and electron beam diffraction (RHEED) demonstrating the B2 order of the Heusler compound with only a small partition of disorder on the Co sites. Magnetic tunneling junctions with Co2Cr0.6Fe0.4Al electrode, AlOx barrier and Co counter electrode were prepared. From the Julliere model a spin polarisation of Co2Cr0.6Fe0.4Al of 54% at T=4K is deduced. The relation between the annealing temperature of the Heusler electrodes and the magnitude of the tunneling magnetoresistance effect was investigated and the results are discussed in the framework of morphology and surface order based of in situ STM and RHEED investigations.