A magnetic thin film is a layer of ferromagnetic or ferrimagnetic material—typically a transition-metal alloy such as permalloy, an amorphous rare-earth transition-metal alloy, or a ferromagnetic oxide—with thickness ranging from nanometres to a few micrometres, deposited onto a non-magnetic substrate so that its magnetic behavior is governed by the constraints of reduced dimensionality and by interfaces rather than by bulk anisotropy alone ^[1]. In such films, the competition between the intrinsic magnetocrystalline anisotropy, the shape anisotropy imposed by the thin geometry, and the interfacial and stress-induced anisotropy determines the orientation of the magnetization and the conditions for magnetization reversal. Because the thickness is comparable to or smaller than characteristic magnetic lengths such as the exchange length and domain wall width, the film supports stripe or single-domain states, spin structures, and magnetization dynamics that differ from those of the corresponding bulk material. The interfaces with the substrate and adjacent layers further modify the magnetic moment and give rise to interfacial anisotropy and interlayer exchange coupling ^[2]. The magnetic thin film is therefore defined as a laterally extended, thin ferromagnetic layer whose magnetic state and reversal are controlled by dimensional, interfacial, and stress anisotropies superimposed on intrinsic exchange interactions ^[3].