Maizel, Rachel E.Wu, ShuangBalakrishnan, Purnima P.Grutter, Alexander J.Kinane, Christy J.Caruana, Andrew J.Nakarmi, PrabandhaNepal, BhuwanSmith, David A.Lim, YoungminJones, Julia L.Thomas, Wyatt C.Zhao, JingMichel, F. MarcMewes, TimEmori, Satoru2025-01-032025-01-032024-10-212331-7019https://hdl.handle.net/10919/123888Energy-efficient spintronic devices require a large spin-orbit torque (SOT) and low damping to excite magnetic precession. In conventional devices with heavy-metal/ferromagnet bilayers, reducing the ferromagnet thickness to approximately 1 nm enhances the SOT but dramatically increases damping. Here, we investigate an alternative approach based on a 10-nm-thick single-layer ferromagnet to attain both low damping and a sizable SOT. Instead of relying on a single interface, we continuously break the bulk inversion symmetry with a vertical compositional gradient of two ferromagnetic elements: Fe with low intrinsic damping and Ni with sizable spin-orbit coupling. We find low effective damping parameters of αeff<5×10-3 in the Fe-Ni alloy films, despite the steep compositional gradients. Moreover, we reveal a sizable antidamping SOT efficiency of |θAD|≈0.05, even without an intentional compositional gradient. Through depth-resolved x-ray diffraction, we identify a lattice strain gradient as crucial symmetry breaking that underpins the SOT. Our findings provide fresh insights into damping and SOTs in single-layer ferromagnets for power-efficient spintronic devices.17 page(s)application/pdfenIn CopyrightArticle - Refereedhttps://doi.org/10.1103/PhysRevApplied.22.044052224Michel, Frederick [0000-0003-2817-980X]2331-7019