Ph. D. thesis is devoted to the established general laws of the influence of temperature and size and concentration effects on the electro- and magnetoresistive properties of FexCo1-x single-layer films and FexCo1-x/Cu/FexCo1-x three-layer film systems. The regularities of formation of crystalline structure and phase composition, behavior of electrophysical (resistivity and TCR), magnetoresistive (anisotropic and giant magnetoresistance) and their interconnection for film alloys and three-layer systems on their basis are established in the interval of thickness d = 5 – 80 nm and concentrations of Fe 10 – 90 at.% in the temperature range of 120 – 700 K. It is found that FexCo1-x film alloy are homogeneous in thickness. Diffusion processes in FexCo1-x/Cu/FexCo1-x film systems with dF = 30 – 40 nm and dN = 10 – 20 nm have been studied and it is shown that they generally preserve the identity of is retained. The thermal and ion-stimulated diffusion causes the mutual penetration of Fe and Co atoms, which are the result of dissociation of FeCo molecules. The regularities in the field dependences of anisotropic and isotropic magnetoresistance for single-layer film materials and three-layer structures with different thicknesses of magnetic and non-magnetic layers and the concentration of components in FexCo1-x layers are established. The concentration and layers thickness ranges, in which anisotropic (positive longitudinal and negative transverse magnetoresistance) and isotropic (negative longitudinal and transverse magnetoresistance) character of magnetoresistance observed, have been identified. The experimental results of the annealing effect on the isotropic magnetoresistance value and the shape of magnetoresistive loops show that the MR behavior and its magnitude in the general case are determined by both the thickness of the ferromagnetic and nonmagnetic layers, and the concentration of the components in the layers. It has been shown experimentally that for all investigated three-layer systems at dF = 25 – 40 nm and dN = 3 – 20 nm, the isotropic character of magnetoresistance as a result of the spin-dependent electron scattering is observed. The maximum value of isotropic MR of 1% at room temperature is observed for Fe0,1Co0,9/Cu/Fe0,1Co0,9 as-deposited system with the same thickness of the magnetic and copper layers of 3 nm. In the case of thermomagnetic step-by-step annealing (through intermediate temperatures of 400, 500 K), the transition from isotropic to anisotropic nature of the magnetoresistance is observed. The exception is samples, in which the granular state forms. For structures with a concentration of Fe 10 – 20 at.% and relatively thin layers (dF = 10 – 20 nm, dN = 5 – 15 nm) the anisotropic nature of the magnetoresistance in the initial state is observed. Annealing at a temperature of 550 K results in an isotropic magnetoresistance, as a result of the granular alloy based on Cu and Co atoms formations. The heat treatment at a temperature of 400, 550 K stimulates an increase in isotropic MR to 3.5 % at room temperature for the samples regardless of component composition and with dF = 20 – 30 nm, dN = 5 – 15 nm. Reducing the measurement temperature from room temperature to 120 K leads to an increase in the isotropic magnetoresistance magnitude by 1.2 – 1.5 times. The obtained experimental results indicate sufficiently high temperature stability of the properties of film structures based on the alloy FexCo1-x and Cu. This allows recommending thermal annealing in vacuum at a temperature of 550 or 700 K directly after the film deposition as one of the stages of the technological process at the formation magnetoresistive elements. It is shown that at the temperature dependencies of the resistivity of three-layer films, regardless of the component concentrations, three characteristic regions are fixed. These regions correspond to the realization of electron scattering on the defects of the crystal structure, grain boundaries, and interfaces, respectively. It has been shown experimentally and theoretically that the TCR value grows at the increase of the FexCo1-x film alloy thickness and the spacer layer thickness in three-layer systems (dF = 30 nm). The experimental and calculated data agree with an accuracy of 20 %. Physical processes in film materials studied from their possible application as sensitive elements with high temperature and time stability of multifunctional sensors and information devices for various purposes.
