  It was experimentally observed that both magnetic anisotropy and spin-orbit
interaction strength change when the magnetization of the nanomagnet is
reversed. This indicates a variation in spin-orbit interaction strength
depending on whether the magnetic field penetrates the interface from a
ferromagnetic to a non-magnetic metal or vice versa. Systematic measurements of
over 100 nanomagnets revealed a consistent, yet unexpected, pattern between
variations in magnetic anisotropy and spin-orbit interactions with
magnetization reversal. These changes align along a single straight line with a
negative slope, suggesting a complex and indirect relationship. Our findings
also suggest the presence of an additional, yet-to-be-identified effect that
influences the change in magnetic anisotropy with magnetization reversal,
beyond the variations in spin-orbit interaction strength. This finding
highlights the complexity of magnetic behavior at the nanoscale and the
critical role of magnetization direction in determining anisotropic properties.
