high temperature superconductivity (htsc) study

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determining the location of holes in htsc lattices by comparing the parameters of the gap tensor using nqr and neg ergash turayev1,2,alisher tursunov2,oyimxol niyozova1,bekzod muhammadiyev1,ikrom raxmonov1 1termiz state university,barkamol avlod street- 43, termiz city, surkhandarya, uzbekistan 2university of tashkent for applied sciences, gavhar street 1, tashkent 100149, uzbekistan (qanvar94@mail.ru) keywords: superconductivity, lattice, holes, tensor, gradient, electric field, atomic centers, ceramics, synthesis, transition temperature, spectroscopy abstract: the nuclear quadrupole resonance (nqr) method on 63.65cu isotopes makes it possible to experimentally determine the total hef on 63.65cu nuclei in high temperature superconductivity (htsc) lattices and, as a result, there is, as a rule, no possibility of comparing experimental and calculated (using the point charge model) parameters of the electric field gradient (efg) tensor. the method of emission mössbauer spectroscopy on the 67cu (67zn) isotope makes it possible to experimentally establish only the contribution to the total efg on 67zn nuclei from ions …

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для применения title к тексту, который должен здесь отображаться. 3 1 introduction one of the main problems in high temperature superconductivity (htsc) physics is determining the localization location of holes, which determine the phenomenon of superconductivity. the most reliable way to identify holes in htsc lattices is considered to be a comparison of the experimentally determined parameters of the electric field gradient tensor (efg) with the results of their theoretical calculation. this method is most effective in measuring and calculating the parameters of the gap tensor. all htscs, as a rule, contain copper, and the parameters of the gap tensor at copper sites are most sensitive to the charges of atomic centers. this work is devoted to the consideration of experimental and theoretical results of determining the parameters of the electric field tensor in copper nodes of уba2cu3o7-x ceramics. the compound is one of the most typical htscs and is …

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e gap from ions and valence electrons by the electrons of the inner shells of the atom. calculation of the parameters of the gap tensor from ions of the crystal lattice can be carried out within the framework of the point charge model. for yba2cu3o7-x ceramics, such calculations were carried out in [2-3]. table 1 summarizes the most typical results for two models of charge distribution of atomic centers in the lattices уba2cu3o7 and уba2cu3o6. let us note, firstly, the satisfactory agreement of the data obtained by different authors, and, secondly, the obvious dependence of the parameters of the gap tensor at copper sites on the charge distribution of atomic centers. experimental methods for determining the parameters of the gap tensor. the most complete experimental information on the parameters of the gap tensor can be obtained by nuclear quadrupole resonance (nqr) and mössbauer spectroscopy methods. these methods are based on …

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nd the local symmetry of its environment is lower than cubic. 2.comparison of results fig.1. 63.65 nqr spectrum in уba2cu3o7 at 1.7 k [30] (a) and 4.2 k [36] (b) when considering the nqr spectra of 63.65cu isotopes in yba2cu3o7-x, it should be bone in mind that in the structure of this compound copper occupies two positions cu (1) and cu (2). in addition, it should be taken into account that the natural mixture of isotopes contains 63cu and 65cu. therefore, four lines should be expected in the 63.65cu nqr spectra of yba2cu3o-x ceramics: 63cu (1), 65cu (1), 63cu (2) and 65cu (2), and the intensities of these lines should be determined by the occupancy of the cu (1), cu (2) (1:2) and the content of the isotopes 63cu (~70%) and 65cu (~30%). indeed (see fig. 1, a), the nqr spectrum of 63.65cu sample yba2cu3o7 consists of two pairs of …

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it is assumed that iron replaces cu(1) and cu(2) atoms in the structure of htsc and the parameters of the mössbauer spectra of 57fe carry information about the symmetry of the local environment of copper atoms [4-6]. the mössbauer transition in 57fe occurs between levels with spins 3/2 and 1/2, so that when impurity iron atoms are in an environment whose local symmetry is lower than cubic, the mössbauer spectrum of 57fe is split into two components. we can formulate the following requirements for mössbauer spectroscopy when used to study copper centers in htsc [7-9]: the probe used must obviously replace copper in the positions of copper atoms: the introduction of an avalet probe into a crystal lattice site should not be accompanied by shell processes, which allows exclude the contribution to the gap from valence electrons. all these conditions are met for mössbauer emission spectroscopy on the 67cu (67zn) …

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determining the location of holes in htsc lattices by comparing the parameters of the gap tensor using nqr and neg ergash turayev1,2,alisher tursunov2,oyimxol niyozova1,bekzod muhammadiyev1,ikrom raxmonov1 1termiz state university,barkamol avlod street- 43, termiz city, surkhandarya, uzbekistan 2university of tashkent for applied sciences, gavhar street 1, tashkent 100149, uzbekistan (qanvar94@mail.ru) keywords: superconductivity, lattice, holes, tensor, gradient, electric field, atomic centers, ceramics, synthesis, transition temperature, spectroscopy abstract: the nuclear quadrupole resonance (nqr) method on 63.65cu isotopes makes it possible to experimentally determine the total hef on 63.65cu nuclei in high temperature superconductivity (htsc) lattices and, as a result, there is, as a ...

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