Spin tunneling in junctions with disordered ferromagnets

TL;DR

This paper demonstrates that amorphous CoFeB exhibits higher tunneling spin polarization than highly textured fcc CoFeB, supported by first-principles calculations aligning with experimental measurements, advancing understanding of spin tunneling in disordered ferromagnets.

Contribution

It provides the first comprehensive comparison of tunneling spin polarization between amorphous and textured CoFeB, supported by both experimental data and first-principles calculations.

Findings

Amorphous CoFeB has higher TSP than textured CoFeB.

First-principles calculations agree with experimental TSP measurements.

Results support existing models of tunneling through disordered systems.

Abstract

We provide compelling evidence to establish that, contrary to one's elementary guess, the tunneling spin polarization (TSP) of amorphous CoFeB is larger than that of highly textured fcc CoFeB. First principles atomic and electronic structure calculations reveal striking agreement between the measured TSP and the predicted s-electron spin polarization. Given the disordered structure of the ternary alloy, not only do these results strongly endorse our communal understanding of tunneling through AlOx, but they also portray the key concepts that demand primary consideration in such complex systems.