Polarized Neutron Reflectivity on Graded Magnetic Alloys for Bulk Spin-Orbit Torques

Spin-orbit torques (SOTs) provide a potentially efficient means to rotate and switch the magnetization in spintronic devices for computing applications. For SOTs to arise, the device structure must possess broken symmetry, which is conventionally achieved via film interfaces. We take a fundamentally different approach that deliberately breaks symmetry within a single magnetic alloy film by continuously varying the composition during film growth. Ideally this produces a constant compositional gradient across the film thickness, but the actual gradient might not be constant due to atomic interdiffusion or phase segregation during growth. Our proposed PNR experiment will quantify both the chemical and magnetic gradients in sputter-grown magnetic alloy films.