Influence of total film thickness on high-frequency magnetic properties of the [FeCoSiN/SiNx]n multilayer thin films

[FeCoSiN/SiNx]n multilayer thin films with different number of layers were fabricated by alternating magnetron sputtering at room temperature with no external magnetic field applied on substrates. A well-defined laminated structure consisting of 7 nm FeCoSiN magnetic layer and 2 nm SiNx insulating layer was observed by transmission electron microscopy (TEM). The static magnetic hysteresis loops of the [FeCoSiN/SiNx]n multilayer thin films measured by vibrating sample magnetometer (VSM) presented an obvious in-plane uniaxial magnetic anisotropy. The dynamic magnetic performance of the [FeCoSiN/SiNx]n multilayer films was studied by vector network analyzer and LLG equation. The results indicated that the total film thickness has slightly impact on the high-frequency magnetic performance of the multilayer thin films. When the total thickness of the [FeCoSiN/SiNx]n multilayer thin films increased to micron level, they could still maintain encouraging high-frequency magnetic properties and electrical property: the ferromagnetic resonance frequency fr=3.74 GHz, real permeability µ′=93.73, and electrical resistivity ρ=196 µΩ cm.