Magnetic properties and microstructure investigation of FeNi films with step-height by Nano-MOKE

Stripe domains in magnetic thin films as well as many of its associated intriguing behaviors has been receiving much attention from researchers for a long time [1]. Stripe domains often present a pseudo-uniaxial anisotropy that aligns along the stripe direction, whose axis can be re-aligned by the application of a sufficiently large in-plane magnetic field [2]. Thus, this pseudo-uniaxial anisot-ropy can be regarded as a rotatable anisotropy that rotates along with the applied field. The magnitude of this stripe domain induced anisotropy can be comparable or even much higher than that of uniaxial anisotropy induced by sputtering deposition in a magnetic field, thus this provide a powerful method to tune ferromagnetic resonance frequencies for high frequency microwave applications [3]. In addition, the omni-directional characteristic of rotatable anisotropy makes it highly flexible for applications. FeNi alloys have a great attention for more than six decades as a consequence of their highly sought-after magnetic characteristics in the development of magnetic data storage systems [4]. In addition, FeNi film is the typical stripe domains structure when the film exceeds “transcritical” state [5], which can be controlled by the film thickness. Significantly, the state of magnetic moment magnetization is crucial adjective status for the pseudo-uniaxial anisotropy and stripe domains.