Ultrathin ferrimagnetic GdFeCo films with very low damping

TL;DR

This study demonstrates ultrathin GdFeCo ferrimagnetic films with very low damping and nearly compensated magnetization, promising for ultrafast, energy-efficient spintronic devices.

Contribution

First demonstration of nearly compensated ultrathin GdFeCo films with low damping suitable for spintronics.

Findings

Achieved near-compensation in 2 nm films with low magnetization

Measured low Gilbert damping constant of 0.0078

Demonstrated potential for ultrafast spintronic applications

Abstract

Ferromagnetic materials dominate as the magnetically active element in spintronic devices, but come with drawbacks such as large stray fields, and low operational frequencies. Compensated ferrimagnets provide an alternative as they combine the ultrafast magnetization dynamics of antiferromagnets with a ferromagnet-like spin-orbit-torque (SOT) behavior. However to use ferrimagnets in spintronic devices their advantageous properties must be retained also in ultrathin films (t < 10 nm). In this study, ferrimagnetic Gdx(Fe87.5Co12.5)1-x thin films in the thickness range t = 2-20 nm were grown on high resistance Si(100) substrates and studied using broadband ferromagnetic resonance measurements at room temperature. By tuning their stoichiometry, a nearly compensated behavior is observed in 2 nm Gdx(Fe87.5Co12.5)1-x ultrathin films for the first time, with an effective magnetization of Meff = 0.02 T and a low effective Gilbert damping constant of {\alpha} = 0.0078, comparable to the lowest values reported so far in 30 nm films. These results show great promise for the development of ultrafast and energy efficient ferrimagnetic spintronic devices.