Synthetic antiferromagnet with Heusler alloy Co2FeAl ferromagnetic layers

TL;DR

This paper demonstrates that Co2FeAl Heusler alloy layers can form stable synthetic antiferromagnets with favorable magnetic properties for high-density magnetic devices, maintaining strong coupling after annealing.

Contribution

It introduces the use of Heusler alloy Co2FeAl in synthetic antiferromagnet structures, showing their stability and advantageous magnetic properties for device applications.

Findings

Strong antiferromagnetic coupling at 0.45 nm Ru thickness

Stable magnetic properties after annealing at 150°C

Potential for all-Heusler spin-valves with high magnetoresistance

Abstract

Heusler alloy Co2FeAl was employed as ferromagnetic layers in Co2FeAl/Ru/Co2FeAl synthetic antiferromagnet structures. The experimental results show that the structure with a Ru thickness of 0.45 nm takes on strongly antiferromagnetic coupling, which maintains up to 150 oC annealing for 1 hour. The structure has a very low saturation magnetization Ms of 425 emu/cc, a low switching field Hsw of 4.3 Oe and a high saturation field Hs of 5257 Oe at room temperature, which are favorable for application in ultrahigh density magnetic read heads or other magnetic memory devices. XRD study testifies that the as-deposited Co2FeAl film is in B2 phase. Therefore Heusler alloys can be used to fabricate SyAF and it is possible to make "all-Heusler" spin-valves or magnetic tunneling junctions with better magnetic switching properties and high magnetoresistance.