The structure and magnetic properties of epitaxial Heusler alloy films (Co2FeGe) deposited on MgO (100) substrates were investigated. Films of 60 nm thickness were prepared by magnetron co-sputtering at different substrate temperatures (TS), and those deposited at room temperature were later annealed at various temperatures (Ta). X-ray diffraction confirmed (001) [110] Co2FeGe || (001) [100] MgO epitaxial growth. A slight tetragonal distortion of the film cubic structure was found in all samples due to the tensile stress induced by the mismatch of the lattice parameters between Co2FeGe and the substrate. Improved quality of epitaxy and the formation of an atomically ordered L21 structure were observed for films processed at elevated temperatures. The values of magnetization increased with increasing TS and Ta. Ferromagnetic resonance (FMR) studies revealed 45° in-plane rotation of the easy anisotropy axis direction depending on the degree of the tetragonal distortion. The film annealed at Ta = 573 K possesses the minimal FMR linewidth and magnetic damping, while both these parameters increase for another TS and Ta. Overall, this study underscores the crucial role of thermal treatment in optimizing the magnetic properties of Co2FeGe films for potential spintronic and magnonic applications.

The dynamic magnetic properties of full Heusler alloy thin films of Co₂FeGe, grown on MgO (001) substrates under different thermal conditions, were investigated. Brillouin light scattering and ferromagnetic resonance measurements revealed that depositing at room temperature followed by annealing at 300 ° C for 1 h produces the best results for maximizing magnetization, exchange stiffness, and minimizing spin-dynamic dissipation in the films, which are desirable characteristics for high-speed spintronic devices. Additionally, strong hybridization of spin waves in the Damon-Eshbach geometry was observed, which is attractive for applications in magnonic signal processing circuits.

Spin dynamics in Al-substituted yttrium iron garnets is investigated using broadband ferromagnetic resonance measurements in the temperature range T=200-360 K. Using the measured data, the resonance field and linewidth as well as their temperature dependence are determined, with implications for the uniformity and overall quality of the samples prepared via different chemical fabrication routes. These key parameters governing the spin dynamics in the material are important for its applications in high-speed spintronic and magnonic devices.

Magnetic properties of N⁢i_46.0⁢M⁢n_36.8⁢S⁢n_11.4⁢C⁢o_5.8/MgO⁡(001) epitaxial thin film, which undergo a martensitic phase transformation from cubic austenitic phase to a twinned orthorhombic martensitic phase at 270 K, were studied by the magnetic resonance at the microwave frequency of 9.45 GHz. It was found that the single resonance line observed in the austenite splits into three lines in the martensitic phase. A theoretical approach was developed to show that the additional resonance lines are caused by the weak antiferromagnetic coupling of the ferromagnetic twin components across twin boundaries. Fitting of the experimental resonance lines to model gives an effective field of antiferromagnetic coupling of about 1.5 kOe, which is two or three orders of magnitude lower than in the conventional antiferromagnetic solids because the number of magnetic ions interacting antiferromagnetically through the twin boundary is much less than the total number of magnetic ions in the twin. This feature shows a strong resemblance between the submicron twinned martensite and artificial antiferromagnetic superlattices, whereby providing a distinctive insight into magnetism of the studied magnetic shape memory material.

The influence of film thickness on the formation of twinning structure, martensitic transformation and magnetoelastic properties of epitaxial films of Ni(Co)MnSn magnetic shape memory alloy is investigated by means of ferromagnetic resonance spectroscopy, synchrotron X-ray diffraction and standard magnetic measurements. It is found that constraints from the film/substrate interface block the martensitic transformation in the 20 nm thick film. The increase of the film thickness results in a progressive stress relaxation and, as a result, the martensitic transformation becomes possible starting from 50 nm. Twinning of the films is required to conserve the films surface area. The elastic energy balance between the film/substrate interface and the twin boundaries leads to the formation of a submicron wide, stripe like, periodical structure of twins, which is of interest for spintronic or magnonic applications. The width of the twin variants increases with the film thickness growth, resulting in the dramatic modification of magnetic properties.

Magnetic properties of Y3AlFe4O12 garnet ceramics have been studied over a wide range of temperature (3 – 370 K) and magnetic fields (up to 2 kOe). Effects of varying the temperature on some of the application-specific magnetic characteristics have been analyzed in detail. With the decrease in temperature, the effective anisotropy constant, KEff, is found to sharply rise below ∼150 K, while the saturation magnetization, Ms, changes only slightly (<20 % within 3 – 250 K). The exchange stiffness, Aex, and spin wave stiffness, D, parameters mirror the relatively smooth behavior of the magnetization at low temperatures but display a rapid drop when T approaches TC ≈ 436 K. The temperature dependence of the domain wall thickness and the critical single-domain size correlate with the corresponding values for pure Y3Fe5O12 (YIG) and are in agreement with the theoretical estimates. We conclude by discussing the ways of how to use the obtained results for tailoring the magnetic properties of YIG-based materials for technological applications.