Registration Number
0221U102107,
0116U002670
, R & D reports
Title
High-Tc superconductivity and competing orderings in inhomogeneous materials.
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Head
Gabovych Oleksandr M., Доктор фізико-математичних наук
Registration Date
28-01-2021
Organization
Institute of Physics of National Academy of Sciences of Ukraine
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Object to study - high-temperature superconductors with charge density waves, break tunnel transitions, layered structures with Coulombic interaction between charges and dipoles.
Purpose — To study, theoretically and experimentally, tunnel break transitions obtained between crystal fragments of layered high-temperature superconductors, elucidate the role of charge density waves (CDWs) and the possibility of their detection in tunnel experiments. To study theoretically the electrostatic interaction between charges and dipoles in layered structures and image forces that arise due to the difference of dielectric constants.
Research methods - measurement of tunnel currents through break junctions, scanning tunnel microscopy, tunnel Hamiltonian method, Green's function method, nonlocal electrostatics method.
Results — It was theoretically shown that the spatial inhomogeneity of order parameters in the electrode material drastically changes the current-volt characteristics (CVCs) of superconducting oxides with CDWs. Namely, they become smoothed and very similar to those observed experimentally. This result was summarized in a corresponding review.
- CVC calculations were performed for incoherent tunneling, when the quasiparticle momentum is not preserved. This model corresponds to the experimental geometry with tunneling along the c-axis of the crystals, i.e. across the layers. On the other hand, the current runs predominantly along the layers in the so-called broken junctions (BJs); in this case the quasiparticle current is coherent. The corresponding calculations were also performed. In particular, it was shown how the disordering effects form the CVCs and how the crystal rotations randomly occurring at the BJ fabrication affect them. The resulting CVCs are in good agreement with our experiments for Bi2Sr2CaCu2O8+δ.
- The electrostatic theory of charge interaction in three-layer media was developed.
Product Description
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Boychuk Valeriy M
Voitenko Oleksandr I
Gabovych Oleksandr M.
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2021-01-28
