The project is aimed at researching and developing prototypes of new magnetic materials, the functional properties of which are formed on the basis of the synergistic effect that occurs in composites with nanoscale components due to exchange, magnetic, electric and force interactions between these components. In accordance with this, and taking into account the scientific and technical reserve of the collective, three types of film composites with different functional objectives are included in the number of research objects:
1) film structures with exchange bias in which due to a certain combination of antiferromagnetic and ferrimagnetic fixing and fixed layers, high stability or anomalies of functional properties with respect to temperature and force effects are realized;
2) artificial metal/polymer multiferroics, for which are solved the problems of developing a package technology combining the formation of metal and polymer layers, and optimizing the parameters of the magnetoelectric effect;
3) granular films with perpendicular magnetic anisotropy as the defining attribute of media for perpendicular magnetic recording of information.
Nanocomposites that realize magnetic functional properties are one of the most perspective and innovative branches of modern materials science. A vivid example is the spin valves, which made a revolution in the technique of recording and reading information on hard disks of computers and are considered as a real basis for nonvolatile random-access memory (MRAM). Among the important properties of such and similar sensor elements relates an internal exchange bias. Its optimization in terms of magnitude, temperature sensitivity, and resistance to force requires investigation of the mechanisms of interlayer exchange interaction in film structures that contain new combinations of ferromagnetic, ferrimagnetic, antiferromagnetic, and nonmagnetic layers with varying structural state and conductivity. In particular, the project pays much attention to structures containing ferrimagnetic Gd-Co or Tb-Co layers with anomalies of magnetic properties such as magnetic compensation or spin reorientation. In this case, the Gd-Co layers with a relatively low coercive force can act as fixed layers in combination with antiferromagnetic Ni-Mn layers, which are characterized by high temperature stability of the
properties. At the same time, Tb-Co layers are considered as a source of exchange pinning of soft magnetic layers of the FeNi-Co system. Composite multiferroics firmly entered in a number of relevant topics of scientific and technical developments. However, their volumetric version is unlikely to find wide application in microelectronics. In this respect, the most promising is the film realization of nanocomposites containing ferromagnetic and polymer layers, which have magnetostriction and spontaneous electric polarization. The creation of such composites involves a complex of physicochemical experiments to develop a technology for obtaining and optimizing the magnetoelectric effect in metal/polymer nanocomposites. On this path, the innovative component of the project is to optimize the state of the interfaces between ferroelectric polymer and metallic magnetostriction layers. In particular, it is proposed to vary their roughness by changing the size of crystallites in metal layers and introducing additional relief-forming spacers. Film nanocomposites exhibiting an exchange bias or a magnetoelectric effect, first of all, are oriented to the sphere of magnetic sensorics. But their role can prove to be very significant in the progress towards the creation of high-density recording of information on magnetic media. The real basis for this is the granular films, which are a system of highly disperse magnetic precipitates localized in a nonmagnetic dielectric matrix. They largely overcomes the limitations of the size of the magnetization reversal areas in continuous high-anisotropic films associated with the presence of a homogeneous and strong exchange interaction. In granular films it is replaced by a weaker magnetostatic interaction between the individual granules, which potentially reduces the size of the magnetic bits of information up to the superparamagnetic level. The main research task in this field is the formation of perpendicular magnetic anisotropy in granular films, which can be solved by searching for optimal compositions of nanocomposites, using structure-forming buffer layers or nanostructured substrates. The novelty of this project is to create granular structures based on amorphous Gd-Co and Tb-Co ferrimagnets and initiate the columnar growth of magnetic metals in the dielectric Al2O3 matrix due to the use of metal buffer layers with a hexagonal structure (Co, Gd, Tb).