Highly spin-transparent nonmagnetic/ferromagnetic interface tailored with an interface argon plasma treatment
Phys. Rev. B 113, 134402 – Published 1 April, 2026
DOI: https://doi.org/10.1103/5mb3-thyn
Abstract
Interfacial spin transparency have been well established as a critical factor in determining the spin current transmission efficiency from heavy metal layer to ferromagnetic layer, thereby influencing the spin-orbit torque (SOT) efficiency in heavy metal/ferromagnetic metal heterostructures. Here, we demonstrate that in situ argon plasma treatment effectively enhances the interfacial spin transparency in Pt/NiFe (Py) bilayers, leading to a substantial improvement in spin-orbit torque efficiency. By optimizing plasma exposure time, a maximum interfacial spin transparency (∼0.98) is achieved, approaching the ideal limit for spin current transmission This results in a 81% enhancement in the dampinglike SOT efficiency, as quantified by spin-torque ferromagnetic resonance measurements. The enhancement of interfacial spin transparency is attributed to a suppression of spin memory loss and spin-flip scattering at the Pt/Py interface, resulting from the reduced interfacial roughness, as directly evidenced by x-ray reflectivity analysis. Furthermore, a linear relationship between interfacial spin transparency and interfacial roughness was obtained. Our findings highlight argon plasma as a simple, scalable, and noninvasive technique for tailoring spin-transport properties at heavy metal/ferromagnetic metal, offering a promising pathway for the development of high-performance spintronic devices.
