Self-biased microwave ferromagnetic performance of patterned Ni80Fe20 thin films

Patterned Ni80Fe20 permalloy films with strip length of 5 mm, strip distance of 40μm and various ferromagnetic (FM) strip widths from 20 to 40μm were prepared by pulse laser deposition and photolithography for study the microwave performance of permalloy films. Comparing with the continuous magnetically isotropic permalloy film, the anisotropy fields HK increase with the decrease of the FM strips’ width. As a result, the ferromagnetic resonance frequency fr is enhanced from 1.71 GHz of continuous film to 2.1 GHz of patterned film with FM strip width of 20μm. The comparison between fr and HK demonstrates that the enhancement of fr can be attributed to the increase of HK due to the shape anisotropy of permalloy strips.