Junyi D. Modification of magnetoresistive characteristics of single crystals Y1-zPrzBa2Cu3O7-δ with a given typology of defect structure by irradiation and high pressure Modification of magnetoresistive characteristics of single crystals Y1-zPrzBa2Cu3O7-δ with a given typology of defect structure by irradiation and high pressure

The study of the temperature dependence of the longitudinal and transverse conductivity of single crystals of Y1-zPrzBa2Cu3O7-δ with different praseodymium contents continues to be one of the most relevant areas of high-temperature superconductivity (HTS) physics, since, despite the large accumulated literature, both the mechanisms and the microscopic nature of high-temperature superconductivity, discovered at the end of the last century in non-stoichiometric superconducting cuprates, remain unclear. The dissertation is dedicated to study of the temperature dependences of the longitudinal and transverse electrical resistance of single crystals of Y1-zPrzBa2Cu3O7-δ with different praseodymium contents, including under conditions of high pressure and radiation exposure. The studied compound is a superconductor of the second kind, its resistive characteristics and anisotropy of transfer processes in the range from the temperature range of the superconducting state to room temperatures are sensitive to structural changes in the crystal lattice. The degree of oxygen doping affects the crystal structure of the compound and radically changes the mechanisms of electrical conductivity of single crystals of Y1-zPrzBa2Cu3O7–δ. On the other hand, the creation of radiation defects of different concentration and morphology in a wide range of radiation doses also affects the specified properties of the studied substance. The dissertation work investigates the regularities and mechanisms of the influence of irradiation on the structure and processes of electrical transfer in compound systems 1 – 2 – 3 based on modern ideas about the nature of conductivity in layered crystalline HTNP compounds. Despite a fairly large number of scientific works devoted to the study of the influence of various factors on electrical transport in the YBa2Cu3O7–δ system, there are almost no works in the scientific literature describing the results of studies on the study of the influence of irradiation on the anisotropy of charge carrier scattering processes both in the normal state and near the superconducting transition, pseudogap and fluctuation anomalies, as well as incoherent electrical transport. Since, according to modern ideas, it is precisely these unusual physical phenomena observed in HTNPs - compounds in the normal (non-superconducting) state, that are important for understanding the physical essence of the microscopic nature of HTNPs, which still remains unclear, despite the more than 37-year history of intensive theoretical and experimental research conducted in this field of solid-state physics. As noted above, irradiation of HTNP compounds with electrons makes it possible, without changing the composition of the samples, to create defects of different concentrations and morphology in them. The creation of an ensemble of defects of a given concentration and nature opens up the possibility of controlling, in particular, the electrical transport properties of the sample in both the normal and superconducting states. Taking into account the prospect of using high-temperature superconductors as ultrasensitive sensors and electric current transmission lines with low energy losses operating in the boiling temperature range of liquid nitrogen, the creation of the so-called "controlled" defect structure in a superconductor is of significant fundamental and practical importance. Due to the complexity of the structure of the studied compound, determining the distribution of defects over the volume of the sample, the stability of the defect composition and the dependence of transport parameters on the type of defects of the crystal structure in a wide temperature range requires significant experimental efforts. The dissertation contains five chapters.