The in-plane rotation of magnetic stripe domains in a 65 nm magnetostrictive Fe0.8Ga0.2 epitaxial film was investigated combining magnetic force microscopy, vibration sample magnetometry, and x-ray resonant magnetic scattering measurements. We analyzed the behavior of the stripe pattern under the application of a bias magnetic field along the in-plane direction perpendicular to the stripes axis, and made a comparison with the analogous behavior at remanence. The experimental results have been explained by means of micromagnetic simulations, supported by energy balance considerations. Fields smaller than ∼ 400 Oe do not induce any stripe rotation; rather, a deformation of the closure domains pattern was evidenced. Larger fields produce a sudden rotation of the stripe structure.

A comprehensive investigation of rotatable anisotropy in a Fe 0.8 Ga 0.2 thin film with a stripe domain structure has been performed comparing static and dynamic measurements. The stripes' domain formation and their rotation under a transverse magnetic field have been imaged by magnetic force microscopy. The rotatable anisotropy field H rot was determined by fitting the frequency evolution of the dipole-dominated magnetostatic spin-wave mode versus the in-plane orientation of the stripe domains, measured by Brillouin light scattering in the absence of any dc or ac magnetic field. We obtained H rot ≈ 1.35 kOe, which is nearly ten times larger than the crystallographic in-plane anisotropy field. By applying a dc magnetic field along the stripes' axis, H rot decreases, and eventually vanishes for saturated in-plane magnetization. At remanence, we established a quantitative relationship between static and dynamic properties, that is, the stripes' rotation angle and the in-plane angle dependence of spin-wave frequency.

In this work we show the development of bulk in-plane magnetic anisotropy in high Gacontent (Ga = 28 at. %) Fe 100-x Ga x thin films as the layer thickness increases. This result is in clear contrast with the generally reported decrease of this anisotropy with the film thickness. We propose the interrelation between the enhancement of the Ga-pair correlations and a collinear distortion of the bcc structure within the sample plane as the origin of the magnetic anisotropy. Our results have been obtained by employing a combination of long and local range structural probe techniques with bulk and surface magnetic characterization techniques. The key point shown in this work is that the inplane structural anisotropy and hence, the magnetic anisotropy, are developed as the layer thickness increases. This fact strongly suggests that the surface to bulk free energy ratio plays a key role in the formation of ordered phases with a distorted bcc cell in Fe 100-x Ga x films with x around 28 at. %. Our work also shows the arising of new phenomena in these high Ga content alloys due to the close correlation between structural and magnetic properties.

Ferromagnetic thin films with moderate perpendicular magnetic anisotropy (PMA) are known to support weak stripe domains provided film thickness exceeds a critical value. In this work, we performed both an experimental and theoretical investigation of a peculiar phenomenon shown by weak stripe domains: namely, the stripe domains reorientation when a dc magnetic field is applied in the film plane along the direction perpendicular to the stripes axis. We focus on bct α′-Fe 8 N 1−x thin films obtained by + N 2 implantation of α-Fe films epitaxially grown on ZnSe/GaAs(001). By using different ion implantation and heat treatment conditions, we show that it is possible to tune the PMA values. Magnetic force microscopy and vibrating sample magnetometer measurements prove the existence of weak stripe domains at remanence, and of a threshold field for the reorientation of the stripes axis in a transversal field. Using a one-dimensional model of the magnetic stripe domains, where the essential parameter is the maximum canting angle of the stripe magnetization out of the film plane, the various contributions to the magnetic energy can be separately calculated. A linear increase of the reorientation threshold field on the PMA is obtained, in qualitative agreement with experimental data in our Fe-N films, as well as in other thin films with weak stripe domains. Finally, we find that also the rotatable anisotropy field linearly increases as a function of the PMA magnitude.

The magnetic properties of an iron nitride thin film obtained by ion implantation have been\ud investigated. N2+ ions were implanted in a pristine iron layer epitaxially grown on ZnSe/GaAs\ud (001). X-ray diffraction measurements revealed the formation of body-centered tetragonal\ud N-martensite whose c-axis is perpendicular to the thin film plane and c-parameter is close to that\ud of alpha' Fe8N. Magnetic measurements disclosed a weak perpendicular magnetic anisotropy (PMA)\ud whose energy density KPMA was assessed to about 105 J/m3. A sharp decline of the in-plane\ud magnetocrystalline anisotropy (MCA) was also observed, in comparison with the body-centered\ud cubic iron. The origin of the PMA is attributed to the MCA of N-martensite and/or stress-induced\ud anisotropy. As a result of the PMA, weak magnetic stripe domains with a period of about 130nm\ud aligned along the last saturating magnetic field direction were observed at remanence by magnetic force microscopy. The application of an increasing in-plane magnetic field transverse to the stripes\ud Htrans highlighted a threshold value above which these magnetic domains irreversibly\ud rotated. Interestingly, below this threshold, the stripes do not rotate, leading to a zero\ud remanent magnetization along the direction of the applied field. The interest of this system for\ud magnetization dynamics is discussed

We report the magnetic anisotropy and domain configuration of cosputtered TbFeGa alloys. The layers were deposited from two targets with compositions TbFe 2 and Fe 3 Ga, respectively. The structural and magnetic properties do not only depend on the composition but also on the growth conditions. Alloys with the same composition but deposited using a DC or a pulsed power source in the TbFe 2 target exhibit a different magnetic anisotropy. The perpendicular magnetic anisotropy, the size and topology of domain patterns can be tailored by changing the evaporation parameters of TbFe 2 . The width of the stripe domain increases from 235 to 835 nm when using the DC source in the TbFe 2 . We correlate this effect with Tb enrichment of the Tb x Fe! x phases present in the samples.

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Two-dimensional arrays of bicomponent structures made of cobalt and permalloy elliptical dots with thickness\ud of 25 nm, length 1 μm, and width of 225 nm, have been prepared by a self-aligned shadow deposition technique.\ud Brillouin light scattering has been exploited to study the frequency dependence of thermally excited magnetic\ud eigenmodes on the intensity of the external magnetic field, applied along the easy axis of the elements. Several\ud modes have been observed while sweeping the field along the major and minor hysteresis loops, encompassing\ud both the parallel and the antiparallel alignment of the magnetization in adjacent permalloy and cobalt dots.\ud Micromagnetic simulations based on the dynamic matrix method enabled us to successfully reproduce the\ud measured evolution of the frequencies with the field, as well as to identify the spatial profiles of the modes.\ud A marked difference in the field dependence of the frequency of some modes has been observed for parallel\ud and antiparallel magnetization configurations, suggesting the possibility of tuning the dynamic response in a\ud reprogrammable way. The role of both static and dynamic magnetic coupling in determining the mode frequency\ud is discussed in detail by studying the frequency evolution as a function of the gap size between the dots