Role of electron scattering in the magnetization relaxation of thin Ni₈₁Fe₁₉ films

Abstract

We observe a strong correlation between magnetization relaxation and electrical resistivity in thin Permalloy (Ni81Fe19, "Py") films. Electron scattering rates in the films were affected by varying film thickness and deposition conditions. This shows that the magnetization relaxation mechanism is analogous to "bulk" relaxation, where phonon scattering in bulk is replaced by surface and defect scattering in thin films. Another interesting finding is the increased magnetization damping with Pt layers adjacent to the Py films. This is attributed to the strong spin-orbit coupling in Pt, resulting in spin-flip scattering of electrons that enter from the Py.