Pulsed laser deposition has been used to grow thin (10–84 nm) epitaxial layers of Yttrium Iron Garnet Y₃Fe₅O₁₂ (YIG) on (111)–oriented Gadolinium Gallium Garnet substrates at different growth conditions. Atomic force microscopy showed flat surface morphology both on micrometer and nanometer scales. X-ray diffraction measurements revealed that the films are coherent with the substrate in the interface plane. The interplane distance in the [111] direction was found to be by 1.2% larger than expected for YIG stoichiometric pseudomorphic film indicating presence of rhombohedral distortion in this direction. Polar Kerr effect and ferromagnetic resonance measurements showed existence of additional magnetic anisotropy, which adds to the demagnetizing field to keep magnetization vector in the film plane. The origin of the magnetic anisotropy is related to the strain in YIG films observed by XRD. Magneto-optical Kerr effect measurements revealed important role of magnetization rotation during magnetization reversal. An unusual fine structure of microwave magnetic resonance spectra has been observed in the film grown at reduced (0.5 mTorr) oxygen pressure. Surface spin wave propagation has been demonstrated in the in-plane magnetized films.

Synthesis of nanosized yttrium iron garnet (Y₃Fe₅O₁₂, YIG) films followed by the study of ferromagnetic resonance (FMR) and spin wave propagation in these films is reported. The YIG films were grown on gadolinium gallium garnet substrates by laser molecular beam epitaxy. It has been shown that spin waves propagating in YIG deposited at 700 °C have low damping. At the frequency of 3.29 GHz, the spin-wave damping parameter is less than 3.6 × 10⁻⁵. Magnetic inhomogeneities of the YIG films give the main contribution to the FMR linewidth. The contribution of the relaxation processes to the FMR linewidth is as low as 1.2%.

The crystalline quality and strain in molecular beam epitaxy (MBE)-grown CaF₂:Sm/Si(111) structures with type-A (nonrotated) and type-B (rotated by 180° in the plane of the interface) epitaxial relationships were characterized by the bivalent samarium photoluminescence technique. It was found from the analysis of X-ray crystal truncation rod (CTR) scattering that the interface spacings along the [111] direction are (1.30±0.03)a ₀ for annealed samples with the type-A and (1.45±0.02)a ₀ with the type-B interface, where a ₀ is the Si(111) spacing. It was also confirmed that Ca atoms occupy T-sites at the interface (atop the atoms of the first Si layer) for the type-A interface. Both the photoluminescence and X-ray measurements indicate that the crystalline quality of type-A CaF₂/Si(111) structures is inferior compared with that of type-B structures.

In the present paper we discuss correlations between crystal structure and magnetic properties of epitaxial ε-Fe₂O₃ films grown on GaN. The large magnetocrystalline anisotropy and room temperature multiferroic properties of this exotic iron oxide polymorph, make it a perspective material for the development of low power consumption magnetic media storage devices. Extending our recent progress in PLD growth of ε-Fe₂O₃ on the surface of technologically important nitride semiconductors, we apply reciprocal space tomography by electron and x-ray diffraction to investigate the break of crystallographic symmetry occurring at the oxide-nitride interface resulting in the appearance of anisotropic crystallographic disorder in the sub-100 nm ε-Fe₂O₃ films. The orthorhombic-on-hexagonal nucleation scenario is shown responsible for the development of a peculiar columnar structure observed in ε-Fe₂O₃ by means of HRTEM and AFM. The complementary information on the direct and reciprocal space structure of the columnar ε-Fe₂O₃ films is obtained by various techniques and correlated to their magnetic properties. The peculiar temperature dependence of magnetization studied by the small-field magnetization derivative method and by neutron diffraction reveals the existence of a magnetic softening below 150 K, similar to the one observed earlier solely in nanoparticles. The magnetization reversal in ε-Fe₂O₃ films probed by X-ray magnetic circular dichroism is found different from the behavior of the bulk averaged magnetization measured by conventional magnetometry. The presented results fill the gap between the numerous studies performed on randomly oriented ε-Fe₂O₃ nanoparticles and much less frequent investigations of epitaxial epsilon ferrite films with lattice orientation fixed by the substrate. Graphical abstract

We study molecular beam epitaxy growth, morphology, crystal structure, and magnetic properties of Co nanoislands on CaF${}_2$/Si(111) surface. In order to have a full appreciation of complex growth kinetics at different stages, a comprehensive study of Co growth on CaF${}_2$ is carried out by atomic force, scanning electron, and transmission electron microscopies in the direct space, as well as by x-ray and electron diffraction in the reciprocal space. These experimental data are complemented by theoretical modeling. Magnetic properties are characterized by magneto-optical Kerr effect and superconducting quantum interference device magnetometries. Key effects influencing the Co growth on fluorite are addressed, including the sticking probability, the preferential nucleation sites, the size and shape time evolution, the dependence of Co morphology on temperature and Co exposure, and the coalescence mechanism. The two-stage deposition technique is developed, whereby the low-temperature seeding stage is used to facilitate Co nucleation, and the follow-up high-temperature deposition yields Co particles with high crystalline quality. Our results enable precise control over the resulting morphology, spatial ordering, and crystal structure affecting the magnetic properties. In particular, it is demonstrated that the transformation from dense to isolated Co nanoparticles leads to the change of the in-plane and out-of-plane magnetic anisotropy and also the sign of polar and longitudinal magneto-optical Kerr effects.