The magnetic properties and micromagnetic structure of [Co/Pt]10 multilayer magnetic films formed by independent variation of the Co and Pt layer thicknesses have been studied. The possibility of the film magnetization parameters manipulation was shown. It is found that the micromagnetic structure of the layers is significantly modified with a change in the thickness of the layers which correlates with the magnetization data. In particular, magnetic force microscopy revealed a system of magnetic skyrmions for a number of structures. The skyrmion density was found to be dependent on the growth conditions which in turn correlates with the shape of the magnetic hysteresis loop. Changing the thickness of the Co and Pt layers makes it possible to control the density of skyrmions in the range from 0.2 to 10.5 µm-2.

The properties of carbon layers (C- layers) formed by thermal decomposition of CCl4 at temperatures of 600–700°C on the surface of gallium arsenide structures fabricated by MOС-hydride epitaxy on n+-GaAs (100) wafers have been studied. The surface morphology of the carbon layers was studied using atomic force microscopy. The structural and optical properties were studied using Raman spectroscopy and reflection spectroscopy. It has been found that in the case of a C layer fabricated at a temperature of 650–700°C, the atomic force microscopy image demonstrates the presence of vertical carbon nanowalls (vertical graphene) located parallel to one of the [110] directions of the GaAs crystal lattice. The characteristics of the bands observed in the Raman spectra correspond to the parameters of the spectra of vertical graphene. The reflection coefficient of such carbon layers significantly decreases (diffuse reflection does not exceed 25% for a layer fabricated at 700°C) in the wavelength range from 0.19 to 1.8 μm. The presence of a significant "absorbing" ability makes the obtained carbon layers promising as a conducting contact in photosensitive semiconductor device structures, which is confirmed by preliminary results of studies of the current-voltage characteristics and spectral dependences of the photocurrent.

The possibilities of controlled exposure to ion irradiation (He+ with an energy of 20 keV and a fluence in the range from 3×1014 to 3×1015 cm–2) as a method for modifying the magnetic properties and domain structure of Co0.35Pt0.65 thin ferromagnetic films have been studied. It was found that the ion irradiation causes a change in the Dzyaloshinsky-Moriya interaction constant and a change in the skyrmion density that correlates with it. This result shows the possibility of homogeneous ion irradiation as a way to control the micromagnetic structure, namely the process of formation of skyrmion states.

The possibility of using He+ ion implantation with an energy of 20 keV for modifying the domain structure and magnetic properties of CoPt films formed by electron beam evaporation with different compositions - Co0.45Pt0.55 and Co0.35Pt0.65 - has been investigated. For the irradiated CoPt samples of both compositions, a decrease in the coercivity (narrowing of the hysteresis loop on the magnetic field dependences of the Faraday angle and magnetization) with an increase in the He+ ion fluence from 2×1014 to 4×1014 cm−2 was found. In this case, the remanent magnetization of the Co0.35Pt0.65 films coincides with the value of saturation magnetization, while for Co0.45Pt0.55, a decrease in the remanent magnetization is observed. Magnetic force microscopy has shown that for the Co0.45Pt0.55 alloy, with an increase in the ion fluence up to 3 × 1014 cm−2, the largest number of isolated circular domains (skyrmions) is formed, while for He+ irradiation with a fluence of 4×1014 cm−2 for Co0.35Pt0.65, in addition to isolated circular domains, 360-degree domain walls (1D skyrmions) are observed. At the same time, the study of CoPt films by the Mandelstam-Brillouin spectroscopy method revealed an increase in the shift between the Stokes and anti-Stokes components of the spectrum and thus a significant increase of the Dzyaloshinsky-Moriya interaction for the irradiated samples. Simulation using the SRIM software showed that the applied ion irradiation causes the asymmetric mixing of Co and Pt atoms and thus, this may underlie the mechanism of the of the ion irradiation on magnetic properties and domain structure in CoPt films.

Abstract A new method for depositing carbon films by the thermal decomposition of carbon tetrachloride (CCl_4) in a hydrogen flux in a reactor for metal-organic chemical vapor deposition (MOCVD) at atmospheric pressure is developed. From the results obtained by Raman spectroscopy, it can be conceived that the carbon layers produced by this method are the disordered nanocrystalline graphite. It is shown that such carbon layers can be used in the technological cycle of the production of gallium-arsenide optoelectronic device structures (among them spin light-emitting diodes with a CoPt injector).

The paper presents examples of the use of pulse force nanolithography, performed with a probe of an atomic force microscope, to form magnetic nanowires, nanocontacts, one- and two-dimensional arrays with characteristic dimensions of about 50-100 nm.

The paper presents a comparative analysis of the magnetic properties of thin films of CoPt, CoPd, FePd alloys. The films were fabricated by electron-beam evaporation, with the variation of a ferromagnetic material content. Studies of the micromagnetic structure showed a decrease in the size of magnetic domains with an increase of the Co content in CoPt and CoPd films, which is associated with the presence of two magnetic phases in the films. Magneto-optical studies have shown abnormally high Faraday angles and the absence of the Kerr effect for CoPt films, which makes them attractive for practical applications in optics. The minimum coercive field values in magnetic field dependences of magnetization, as compared with other films, were obtained for FePd films, which is also associated with the peculiarities of the magnetic structure.

The effect of ion irradiation on the magnetic properties of films of the ferromagnetic CoPt alloy made by the method of electron beam evaporation is investigated. It has been established that with an increase in the He+ ion fluence from 1×1013 to 1×1016 cm-2, a decrease in the coercive field and an increase in the planar component of the axis of easy magnetization are observed. Using magnetic force microscopy and Mandel'shtam-Brillouin spectroscopy, it was shown that with certain ion fluence (3 × 1014 cm-2), the formation of isolated round domains representing magnetic skyrmions is observed in the CoPt layer.

Abstract —A possibility of changing the magnetic type structure of multilayer CoPt films under action of the magnetic field of the atomic force microscope probe is demonstrated. A new method of non-contact magnetic-force measurements based on artificial increase in the electrostatic interaction between the probe and the film is proposed. This method enables one to controllably change the distance between a probe and a film, thus changing the strength of the magnetic interaction. Using it, one can create from a uniformly magnetized state both a labyrinth domain structure and isolated domains, which are apparently magnetic skyrmions.

Abstract —Layers of InAs, InSb, and GaSb semiconductors highly doped with iron during their growth by the method of pulsed laser deposition are studied experimentally. The best temperatures for layer formation on GaAs (100) substrates are: 250°C (InSb : Fe), 300°C (InAs : Fe), and 350°C (GaSb : Fe). At high Fe concentration (over 10 at %) the layers display ferromagnetic properties expressed in emergence of a hysteresis curve within the magnetic field dependences of the Hall resistance, negative magnetoresistance, and in some cases, ferromagnetic-type magnetization at measurements at room temperature. The atoms of iron do not change the type of layer conductivity; InAs : Fe and InSb : Fe layers possess n -type conductivity, and GaSb : Fe layers display p -type conductivity due to their intrinsic point defects.

Проведено исследование магнитных свойств пленок Co45Pt55, полученных методом электронно-лучевого испарения в вакууме. Измерениями магнитооптических эффектов Фарадея и Керра подтверждено наличие оси легкого намагничивания, расположенной перпендикулярно поверхности Co45Pt55. Показано, что перпендикулярная магнитная анизотропия и остаточная намагниченность, сохраняются при 300 K в течение длительного времени. Методами магнитно-силовой микроскопии исследованы магнитные характеристики поверхности слоев Co45Pt55, обнаружены "круговые" подвижные магнитные структуры. На основе гетеронаноструктур In(Ga)As/GaAs сформированы спиновые светоизлучающие диоды с контактными слоями Co45Pt55, для которых регистрируется циркулярно-поляризованное излучение в отсутствие внешнего магнитного поля. Работа выполнена в рамках реализации государственного задания (проекты N 8.1054.2014/К и N 3.285.2014/K,) Минобрнауки РФ, при поддержке РФФИ (гранты N 15-02-07824\_а, 15-38-20642мол\_а\_вед и 16-07-01102\_а) и гранта Президента РФ (МК-8221.2016.2).

Методами магнитно-силовой микроскопии исследованы два различных типа образцов: тонкие пленки металлов и пленки ферритов-гранатов. Отмечено, что в гранатовых пленках магнитно-силовая микроскопия позволяет судить лишь о доменной структуре приповерхностного слоя. Рассмотрены вопросы, связанные с проведением измерений во внешних магнитных полях, влиянием магнитного поля зонда на исследуемую доменною структуру, а также с использованием поляризационной магнитооптики в комбинации с магнитно-силовой микроскопией.