Evolution of the interfacial perpendicular magnetic anisotropy constant of the Co${}_2$FeAl/MgO interface upon annealing

Abstract

We investigate thickness series of films of the Heusler alloy Co${}_2$FeAl in order to study the effect of annealing on the interface with a MgO layer and on the bulk magnetic properties. Our results reveal that while the perpendicular interface anisotropy constant $K_{\mathrm{S}}^{\perp }$ is zero for the as-deposited samples, its value increases with annealing up to a value of $1.14\pm 0.07$~mJ/m${}^2$ for the series annealed at 320${}^{\mathrm{o}}$C and of $2.07\pm 0.7$~mJ/m${}^2$ for the 450${}^{\mathrm{o}}$C annealed series owing to a strong modification of the interface during the thermal treatment. This large value ensures a stabilization of a perpendicular magnetization orientation for a thickness below 1.7~nm. The data additionally shows that the in-plane biaxial anisotropy constant has a different evolution with thickness in as-deposited and annealed systems. The Gilbert damping parameter $\alpha$ shows minima for all series for a thickness of 40~nm and an absolute minimum value of $2.8\pm 0.1\cdot 10^{-3}$. The thickness dependence is explained in terms of an inhomogenous magnetization state generated by the interplay between the different anisotropies of the system and by crystalline disorder.

6 pages, 5 figures

References in corpus (3)

• A 4-fold-symmetry hexagonal ruthenium for magnetic heterostructures exhibiting enhanced perpendicular magnetic anisotropy and tunnel magnetoresistance
• Magnetic and structural properties of Co2FeAl thin films grown on Si substrate
• Perpendicular magnetic anisotropy in Co${}_2$Fe${}_{0.4}$Mn${}_{0.6}$Si

Cited by in corpus (1)

• Separation of the two-magnon scattering contribution to damping for the determination of the spin mixing conductance