Magnetic order parameter controls Gilbert damping parameter in heterostructures
Phys. Rev. Materials 9, 074407 – Published 15 July, 2025
DOI: https://doi.org/10.1103/f2w4-c4q8
Abstract
In this investigation, we explored the temperature dependence of the damping parameter in Py/Cu/Gd/Ta structures using broadband ferromagnetic resonance. A noteworthy escalation in the Gilbert damping factor of Py was noted upon cooling below the magnetic ordering temperature of the Gd, particularly when Gd layer thicknesses exceed 20 nm. This observed enhancement is attributed to the phenomenon of spin pumping into the Gd layer through the Cu buffer layer. Magnetic order increases Gd's performance as a spin sink, thereby enhancing the damping parameter of Py via increased relaxation of spin current pumped into the Gd. Contrary to previous work that suggest damping enhancement in this system was due to the antiferromagnetic coupling between Py and Gd layers and not to magnetic order, the present study utilizes 10 nm thick Cu to prevent such coupling. This allows us to conclude that robust magnetic order in the spin sink enhances the damping parameter.
