Origin of mixed anisotropy in crystalline Permalloy and amorphous Cobalt thin films individually deposited on Si substrate

Abstract

Magnetic anisotropy (MA) plays a crucial role in deciding both static and dynamic behaviour of magnetic thin films. It controls various phenomena, such as magnetization reversal, domain formation, domain-wall motion, spin-wave generation, and spin-wave propagation etc. We investigate the mixed anisotropies in face-centred-cubic Permalloy (fcc-Py) and amorphous Cobalt (a-Co) thin films deposited via rf magnetron sputtering on Si (100) substrate with thicknesses, d = 5-125 nm and t = 5-150 nm, respectively. X-ray diffraction technique, atomic force microscopy, and vibrating sample magnetometry are employed to study the structural, morphological, and magnetic properties. We adopt a qualitative approach to understand the nature of different anisotropies present in both materials. Mixed anisotropies evolve with film thicknesses for both fcc-Py and a-Co films. The role of growth conditions in the emergence of specific anisotropies is discussed in detail. An alteration of the magnetization easy axis from the conventional in-plane orientation is evidenced due to the collective influence of these mixed anisotropies. Based on the dominance of anisotropy components, their origin, and the direction of magnetization tilt, we categorize our samples as belonging to specific regimes. Introduction of magnetization tilt has been proven to be an extremely innovative way to improve the performance of spintronic devices so far. The one-to-one comparison between a sputter-deposited crystalline and an amorphous magnetic material could be beneficial for building a stronger foundation for that.