Effects of hydrogen absorption on magnetism in Ni 80 Fe 20 / Y / Pd trilayers

The effects of hydrogen absorption on the effective magnetization $(4\ensuremath{\pi}{M}_{\mathrm{eff}})$, gyromagnetic ratio $(\ensuremath{\gamma})$, Gilbert damping constant $({\ensuremath{\alpha}}_{\mathrm{G}})$, and the inhomogeneous linewidth broadening $(\mathrm{\ensuremath{\Delta}}{H}_{0})$ in $\mathrm{Py}(x)/\mathrm{Y}$(16 nm)/Pd(15 nm) trilayer films ($x=2$, 3, 5, 8, 10, 20, 40 nm) were investigated with ferromagnetic resonance (FMR), transmission electron microscopy, and vibrating sample magnetometry. In the presence of a hydrogen atmosphere, the samples show a reduction of their FMR linewidth which is found to stem purely from a reduction of the inhomogeneous linewidth broadening. This is attributed to a rearrangement of atoms at the Py/Y interface in the presence of hydrogen, making the Py/Y interface more homogeneous. In addition, a reduction of $4\ensuremath{\pi}{M}_{\mathrm{eff}}$ was seen for all samples in the hydrogen atmosphere which is typical for an increase of the interfacial perpendicular magnetic anisotropy at the Py/Y interface.