Paramagnetic Fe_xTa_{1-x} alloys for engineering of perpendicularly magnetized tunnel junctions

TL;DR

This paper investigates ferromagnetic exchange coupling through amorphous paramagnetic Fe-Ta alloys, demonstrating tunable properties that are promising for engineering perpendicularly magnetized tunnel junctions in nano-magnetic systems.

Contribution

It reveals how exchange coupling depends on alloy composition and temperature, enabling improved design of magnetic tunnel junctions with tailored interlayer interactions.

Findings

Exchange coupling depends exponentially on spacer thickness.

Coupling scales with Fe-Ta alloy susceptibility.

Materials can suppress dead layers and act as diffusion barriers.

Abstract

Exchange coupling between two magnetic layers through an interlayer is of broad interest for numerous recent applications of nano-magnetic systems. In this Letter we study ferromagnetic exchange coupling through amorphous paramagnetic Fe-Ta alloys. We show that the exchange coupling depends exponentially on spacer thickness and scales with the Fe-Ta susceptibility, which can be tuned via the alloy composition and/or temperature. Such materials are of high interest for the engineering of perpendicularly magnetized CoFeB-MgO based tunnel junctions as it enables ferromagnetic coupling of magnetic layers with differing crystalline lattices, suppresses dead layers and can act as an inter-diffusion barrier during annealing.