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Information × Registration Number 0213U002984, 0108U000255 , R & D reports Title Investigation of the properties of the nanocrystals and nanostructures, caused by dimension effects for interactions and current carriers. popup.stage_title Head Ryabchenko S.M., Registration Date 20-02-2013 Organization Institute of physics NASU popup.description2 The theme covers the development of researches of the diluted magnetic semiconductors, the magnetic nano-structures such as magnetic films, the granular films of the type: ferromagnetic metallic nanogranule - a non-conducting and not magnetic matrix , studying of magnetic properties of thin epitaxial films of HTSC, and also theoretical studies of the magnetic systems with magneto-structural quantum phase transitions (QPT). The studying of the nano-structures with the diluted magnetic semiconductors (DMS) included researches of the optically-detected spin resonance in quantum wells from semimagnetic semiconductors and research surface nano-layers semiconductor SiC with the implanted magnetic ions (Mn, Fe). It has been shown that an ionic implantation, in this case, leads to occurrence of the DMS nano-layers, but these layers do not become ferromagnetic. QPT in the dimeric antiferromagnetic (AFM) and in van-Vleck AFM are described within the framework of the Landau theory on the basis of consideration of reorganization of the basic state. Spin configurations and the critical fields for van-Vleck systems with the spin on the node S=1, in which the regrouping of the one-ionic levels occurs without of the multiplicity change, are found. The studies of the magnetic properties of thin HTSC epitaxial films have allowed to establish a role of a dispersion of the local value of critical temperature of the superconducting transition, Tc, for the temperature dependences of a critical current density in a film and of the flux creep in immediate vicinity to Tc. The main goal for the studying of the nano-granular magnetic films was questions of anisotropy of these objects and studying of influence of the intergranular interactions on the formation of collective states of the superparamagnetic particles ensembles - superferromagnetic and superspinglass ones. The properties of films in which magnetic anisotropy (or its intraplane contribution) are caused by the anisotropy of granules, and a direction of an easy axis of magnetization of this single-granule anisotropies are similar for all granules due to growth conditions, are investigated. The systems both with the growth-induced intraplane anisotropy of granules and with perpendicular to the film plane ones were investigated. It is found, that occurrence of a superferromagnetic state is shown for such films in occurrence of the coercive fields at the temperature of the superferromagnetic ordering, if it is higher than a blocking temperature for the granules. Harbingers of the superspinglass state onset are found in angular dependence of coercivity near to a "difficult" direction of magnetization. The features of a ferromagnetic resonance in a non-uniformly magnetized state of the films with perpendicular anisotropy and the features of magnetization of the films with perpendicular anisotropy in the inclined magnetic field were found. It has been investigated and explained the phenomenon of the low-field positive magneto-resistance in the granular magnetic films. The results of researches matter for development of fundamental - scientific representations about the magnetic nano-structures of the mentioned types. They can be used in the further researches and in educational courses. They have as well practical value for use at characterization of the magnetic nano-structures and for choice of their growth regimes for use in tasks of the information record and for using in others devices of spintronics. Product Description popup.authors Бондар Олександр Васильович Калита Віктор Михайлович Ковальчук Денис Георгієвич Комаров Альберт Васильович Кулик Микола Миколаєвич Лозенко Альберт Федорович Рябченко Сергій Михайлович Терлецький Олег Валентинович Тимофієв Андрій Олександрович Троценко Павло Олександрович Чорноморець Матей Петрович popup.nrat_date 2020-04-02 Close