Work number - M 10 AWARDED
Authors: Polek T.I., Polishchyk D.M.
Theseriesofpublications wasnominated by Scientific council of Institute of magnetism NASU and MESU.
Materials with colossal magnetoresistance (CMR) are highly promising for the use in multifunctional nanostructures of spintronics and information technologies. However, the transition to nanoscale sizes strongly changes their physical parameters. This work is aimed at elucidation of the character of transformation of magnetic properties of CMR-materials under chemical substitutions and transition to nanosizes. To accomplish the task, a complex of experimental techniques was employed, namely, magnetic, electric, magnetoresistance and X-ray methods, combined with electron spin resonance technique. Taking into account the complicated character of the processes, experimental investigations were complemented with computer simulation. As a result, the regularities of the transformation of magnetic phase composition of the La(Sr)MnO3-based samples have been specified. The specific features of the change of magnetic interactions resulted from the changes in the symmetry of crystal lattice, caused by structural transitions and substrate-induced deformations (for thin film samples), have been determined. For the ultrathin films and nanocrystalline materials, the critical sizes have been found, below which magnetic state and magnetic interactions display substantial changes. As a result of the investigations, the direction to purposefully control the properties of CMR-materials are outlined, which makes it possible to achieve competitive parameters when they are used in nanostructures.