Shape-induced ultrahigh magnetic anisotropy and ferromagnetic resonance frequency of micropatterned thin Permalloy films.

Magnetic anisotropy Hk>200 Oe was observed from bar-shaped Permalloy strips. The film was deposited on sputtered Cr seed layer by electroplating under ∼800 Oe external magnetic field. Tiny degradation of Hk was observed after 30 min postannealing at 400 °C in the absence of external magnetic field. The Permalloy strip with in-plane aspect ratio of 40:1 showed the ferromagnetic resonance at ∼5.3 GHz. The ferromagnetic resonance frequency and magnetic anisotropy decreased to ∼1 GHz and ∼50 Oe, respectively, as the in-plane aspect ratio reduced from 40:1 to 10:1. In comparison, Permalloy strips plated on combined Ti/TiN seed layers did not show clear anisotropy features. [ABSTRACT FROM AUTHOR]