[en] The review concerns the results of studies reported in the last decade and concerning oxide ferromagnetic semiconductors which retain the spin orientation of charge carriers above room temperature. Particular attention is paid to methods of preparation of diluted magnetic semiconductors. Methods of synthesis and peculiarities of the physicochemical properties of films and coatings based on ferromagnetic semiconductors are described and prospects for application of these compounds as materials for spintronics are discussed. The bibliography includes 160 references.

[en] We describe synthesis of submicron Y_3Fe_5O_1_2 (YIG) films sputtered on Si substrates and present results of the investigation of ferromagnetic resonance (FMR) and spin waves in YIG/SiO_2/Si structures. It is found that decrease of the annealing time leads to essential reduction of the FMR linewidth ΔH and, consequently, to reduction of relaxation losses of spin waves. Spin-wave propagation in in-plane magnetized YIG/SiO_2/Si structures is studied. We observe the asymmetry of amplitude-frequency characteristics of the Damon-Eshbach spin waves caused by different localizations of spin waves at the free YIG surface and at the YIG/SiO_2 interface. Growth of the generating microwave power leads to spin-wave instability and changes amplitude-frequency characteristics of spin waves

[en] Heterostructures of silicon dioxide films containing cobalt nanoparticles SiO₂(Co) grown on GaAs substrate exhibit at room temperature high values of magnetic field enhancement of photocurrent in the vicinity and above the GaAs bandgap of ∼1.4 eV. For photon energies E above the GaAs bandgap, the photocurrent significantly increases, while the avalanche process is suppressed by the magnetic field, and the current flowing through the heterostructure decreases. The photocurrent is enhanced in the SiO₂(Co 60 at. %)/GaAs heterostructure at the magnetic field H = 1.65 kOe by a factor of about ten for the photon energy E = 1.5 eV. This phenomenon is explained by a model describing electronic transitions in magnetic fields with the spin-dependent recombination process at deep impurity centers in the GaAs interface region

[en] 

Abstract

: Yttrium iron garnet (YIG) (Y₃Fe₅O₁₂) films have been grown on single-crystal lithium niobate (LiNbO₃) ferroelectric substrates by ion beam sputter deposition. X-ray diffraction, electron microscopy, magnetic measurement, and spin wave propagation results for the Y₃Fe₅O₁₂ films suggest that they can be used in devices for mutual conversion of magnetic and electrical quantities.

[en] We describe synthesis of submicron Y₃Fe₅O₁₂ (YIG) films sputtered on GaAs-based substrates and present results of the study of ferromagnetic resonance (FMR), spin wave propagation and interaction between spin excitations and 2D electrons in interface layer in YIG/AlO_x/GaAs-heterostructures. It is found that the contribution of the relaxation process to the FMR linewidth is about 3.6%–6.6% of the linewidth . The main contribution to the FMR linewidth of sputtered YIG films is given by a magnetic profile inhomogeneity. Transistor structures with two-dimensional electron gas (2DEG) channels in AlO_x/GaAs interface governed by YIG-film spin excitations are designed. An effective influence of spin excitations on the current flowing through the GaAs 2DEG channel is observed. It is found that the light illumination results in essential changes in the YIG-film FMR spectrum of transistor structures—an increase of the 2DEG current induced by light leads to an inverse effect, which represents essential changes in the FMR spectrum. (paper)

[en] Film samples of nominal Mg(Fe_0.8Ga_0.2)₂O_4-δ composition were obtained on Si(100) substrates by oxygen-ion-beam sputtering of a Mg(Fe_0.8Ga_0.2)₂O_4-δ ceramic target. The film thicknesses were ∼200 and ∼400 nm. Field dependences of the specific magnetization of ∼200-nm films annealed at different temperatures (800–1000°C) have been measured. The crystal structure, surface morphology, and magnetic characteristics of films of different thicknesses (∼200 and ∼400 nm) are investigated. The reasons for the discrepancy between the specific magnetizations of the films obtained and their ceramic analog are discussed.

[en] The structural and magnetic properties of a cobalt nanolayer placed between a silicon substrate and a protective gold layer are studied. At a cobalt layer mass thickness of 1-2 nm, a nanoisland structure is shown to form. This thickness range is characterized by a local maximum of the magnetooptical Kerr effect and enhanced nonlinear optical and magnetic nonlinear optical responses at the second-harmonic frequency. This enhancement can be caused by the excitation of local surface plasmons and an increase in the local fields at the probing-radiation and second-harmonic frequencies in metallic nanoislands. The surface-sensitive nonlinear magnetooptical Kerr effect at the second-harmonic frequency is maximal at a cobalt layer thickness of about 2 nm, which corresponds to the characteristic scale of magnetization formation in the near-surface layer in cobalt.

[en] 

Abstract—

Scanning electron microscopy results demonstrate that coupling of the ferromagnetic and ferroelectric components in a Co/PbZr_0.45Ti_0.55O₃/Co thin-film structure, resulting in a considerable magnitude (several to tens of mV/A) of a low-frequency magnetoelectric effect at room temperature, extends to a depth of up to 20 μm. This makes it possible to optimize the thickness of the PbZr_0.45Ti_0.55O₃ substrate and enhance the performance of such structures for use as sensing elements in information storage/processing devices and magnetic field sensors based on the magnetoelectric effect.

[en] Using the space-resolved Brillouin light scattering spectroscopy, we study the frequency and wavenumber selective spin-wave channeling. We demonstrate the frequency selective collimation of spin-wave in an array of magnonic waveguides, formed between the adjacent magnonic crystals on the surface of yttrium iron garnet film. We show the control over spin-wave propagation length by the orientation of an in-plane bias magnetic field. Fabricated array of magnonic crystal can be used as a magnonic platform for multidirectional frequency selective signal processing applications in magnonic networks.

[en] Yttrium-iron garnet (YIG) film was deposited by ion-beam sputtering on gadolinium gallium garnet (GGG) substrate with the periodical array of grooves ion-etched in its surface. Spin-wave excitations in the fabricated structure were studied by the ferromagnetic resonance (FMR) method and by the spin-wave spectroscopy. Results were compared with ones for the YIG film deposited on GGG substrate without the periodical relief. (paper)