We present a study of the properties related to the magnetization reversal process in two thin-film samples with magnetic stripe domains: Fe0.82Ga0.18 (Fe-Ga) and Ni0.81Fe0.19 (permalloy). In Fe-Ga thin films, we focus on magnetization reversal driven by thermal activation by considering the magnetic viscosity behavior. The results suggest that the reversal process occurs gradually, where the magnetization switches direction via similar to 10 nm-long jumps of the magnetic domain walls. On the other hand, vectorial hysteresis loops were performed in permalloy thin films with the aim to study the behavior of the transverse magnetization component (perpendicular to the applied field) during the magnetization reversal process. We show that the measurement of the transversal magnetization component shows a much higher sensitivity for the determination of the in-plane magnetic anisotropy than the usual hysteresis loops where the magnetization is parallel to the applied field. Moreover, this allows to highlight the competition between the intrinsic and rotatable anisotropies in thin films that present stripe domains.

In ferromagnetic thin films, the presence of an out-of-plane component of the magnetic anisotropy may induce a transition from planar to stripe-like magnetic domains above a critical thickness, t(c). Because of the changes in the domain structure, important changes in the magnetization reversal mechanisms are observed. We present the analysis of the magnetization reversal in FePt thin films, where this phenomenon is observed, through the experimental observation of magnetic domains by magnetooptic Kerr effect microscopy. The observed reversal mechanisms are strongly dependent on the thickness of the sample. For tt(c), the stripe-domain structure determines the magnetization reversal.

We report the synthesis and characterization of thin films of the Weyl semimetal NbAs grown on GaAs (100) and GaAs (111)B substrates. By choosing the appropriate substrate, we can stabilize the growth of NbAs in the (001) and (100) directions. We combine x-ray characterization with high-angle annular dark field scanning transmission electron microscopy to understand both the macroscopic and microscopic structure of the NbAs thin films. We show that these films are textured with domains that are tens of nanometers in size and that, on a macroscopic scale, are mostly aligned to a single crystalline direction. Finally, we describe electrical transport measurements that reveal similar behavior in films grown in both crystalline directions, namely carrier densities of $\sim 10^{21} - 10^{22} $

We report the impact of the tungsten crystal structure on the spin transport properties of permalloy/tungsten bilayers grown by sputtering on (100) silicon. The microstructure of the tungsten layer was modified using a reactive N $$_2$$ /argon mixture during the fabrication process. The analysis combines ferromagnetic resonance and inverse spin Hall effect (ISHE) experiments. A correlation with the electrical and structural characterization indicates that an initial $$\beta$$ -W stabilization notably improves the measured ISHE signal. Nevertheless a subsequent increment of the N $$_2$$ pressure degrades the signal, probably due to higher interstitial nitrogen and degradation of the interface quality. The interplay between the resistivity and disorder gives an optimal growth condition to enhance the tungsten spin current sensing property.

Understanding the effect of fabrication conditions on domain wall (DW) motion in thin films with perpendicular magnetization is a mandatory issue in order to tune their properties aiming to design spintronics devices based on such phenomenon. In this context, the present work intends to show how different growth conditions may affect DW motion in the prototypical system Pt/Co/Pt. The trilayers were deposited by dc sputtering, and the parameters varied in this study were the Co thickness, the substrate roughness and the base pressure in the deposition chamber. Magneto-optical Kerr effect-based magnetometry and microscopy combined with x-ray reflectometry, atomic force microscopy and transmission electron microscopy were adopted as experimental techniques. This permitted us to elucidate the impact on the hysteresis loops and on the DW dynamics, produced by different growth conditions. As other authors, we found that Co thickness is strongly determinant for both the coercive field and the DW velocity. On the contrary, the topographic roughness of the substrate and the base pressure of the deposition chamber evidence a selective impact on the nucleation of magnetic domains and on DW propagation, respectively, providing a tool to tune these properties.

FePt ferromagnetic polycrystalline thin films of equiatomic composition deposited on oxidized Si (100) substrates have been studied as a function of film thickness by means of dc magnetization and ferromagnetic resonance measurements. Films in the as-deposited state have a moderate texture along the [111] direction as confirmed by X-ray diffraction experiments. In-plane magnetic hysteresis loops show an increasing coercive filed and a decreasing remanent magnetization when the film thickness increases from 10 to 100 nm. Thicker films (t= 60 and 100 nm) reverse magnetization in a two step process, characteristic of samples that present stripe-like magnetic domains. Ferromagnetic resonance in thinner films (which have an almost square hysteresis loop) is characterized by a single resonance line related to the uniform precession of the magnetization, which correlates well with the static magnetic measurements. The two thicker films show an additional resonance line when the magnetic field is applied at, or very close to, the film plane normal. This line is shifted to lower fields from the main resonance by 400-700 Oe and is observed at both X and Q-bands with a field separation that depends on film thickness. These additional resonances, can be originated in the presence of standing spin waves in the thicker films which could not be observed in the thinner ones.