  This study introduces a method to measure strength of spin-orbit interaction
(SO) in a nanomagnet, investigating fundamental phenomena governing magnetic
anisotropy. The method explores the fundamental property of SO in its linear
proportionality to the external magnetic field, a relationship validated
through experimental observation. Systematic study of SO in FeCoB nanomagnets
reveals distinct SO behaviors in bulk and at an interface, its substantial
disparities in single- and multi-layer nanomagnets, intriguing periodic
oscillations in SO strength, and the systematic relationship between SO
strength, demagnetization field, and magnetic anisotropy based on surface
imperfections. These findings provide crucial insights into diverse spin-orbit
interaction behaviors, crucial for understanding and optimizing magnetic
anisotropy and nanomagnet properties.
