Ultra-low Gilbert damping and self-induced inverse spin Hall effect in GdFeCo thin films

• Published in: Journal of applied physics 2024-11, Vol.136 (20)
• Main Authors: Pradhan, Jhantu, Devapriya, M. S., Mondal, Rohiteswar, Uzuhashi, Jun, Ohkubo, Tadakatsu, Kasai, Shinya, Murapaka, Chandrasekhar, Haldar, Arabinda
• Format: Article
• Language: English
• Subjects: Anisotropy; Broadband; Current carriers; Damping; Electrical measurement; Electromagnetism; Ferrimagnetic materials; Ferromagnetic materials; Ferromagnetic resonance; Film thickness; Gadolinium; Hall effect; Orbital mechanics; Spin dynamics; Spin-orbit interactions; Spintronics; Substrates; Thick films; Thickness measurement; Thin films; Transition metal alloys; Transition metals; Transport properties
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0231132

Ferrimagnetic materials have garnered significant attention due to their broad range of tunabilities and functionalities in spintronics applications. Among these materials, rare earth-transition metal GdFeCo alloy films have been the subject of intensive investigation due to their spin-dependent transport properties and strong spin–orbit coupling. In this report, we present self-induced spin-to-charge conversion in single-layer GdFeCo films of different thicknesses via an inverse spin Hall effect. A detailed investigation of spin dynamics was carried out using broadband ferromagnetic resonance measurements. The anisotropy constant and the effective g-factor are found to decrease with thickness, and they become nearly constant for thicknesses beyond 25 nm. A remarkably low damping constant of 0.0029 ± 0.0003 is obtained in the 43 nm-thick film, which is the lowest among all previous reports on GdFeCo thin films. Furthermore, we have demonstrated a self-induced inverse spin Hall effect, which has not been reported so far in a single-layer of GdFeCo thin films. Our analysis shows that the inverse spin Hall effect becomes increasingly dominant over the spin rectification effect with increasing film thickness. The in-plane angular-dependent voltage measurement of the 43 nm-thick film reveals a spin pumping voltage of 1.64 μV. The observation of spin-to-charge current conversion could be due to the high spin–orbit coupling element Gd in the film as well as the interface between GeFeCo/Ti and substrate/GdFeCo of the films. Our findings underscore the potential of GdFeCo as a prime ferrimagnetic material for emerging spintronic technologies.