The Holes on Oxygen Sites and Bsc Physical Picture in High-Temperature Superconductors
Abstract
As it follows from the experiment , magnetic and transport cuprate properties are connected with different groups of electron states: magnetic states are localized on the ions CuZ+, whereas current carriers are holes in valence band, genetically related to 2p-oxygen states which overlap weakly with d-copper shell. At a sufficiently large concentration of carriers a magnetic system seems to be in a singlet state and its spinless (singlet) excitation modes are hybridized with phonon modes of the corresponding symmetry. These "dressed" phonons are the main source of interaction between holes, resulting in the formation of the Cooper pairs and superconductivity which in the first approximation can be described in the framework of formalism common for an electron-phonon system. A change of energy of a phonon system at a superconducting transition makes an essential contribution into thermodynamios of a superconducting state. Under certain conditions this transition may become 1-t kind one. A more detailed description requires an exceeding beyond the framework of the Migdal approximation which accuracy in the case of a quasi-two-dimensional hole spectrum is characterized by the parameter u\~(hbar overline w /E_F )l_n E_F /hbar overline w (EF is the Fermi energy of holes, hbar overline w is an average phonon energy)…
- Publication:
-
High Temperature Superconductivity from Russia. Edited by LARKIN A I ET AL. Published by World Scientific Publishing Co. Pte. Ltd
- Pub Date:
- 1989
- DOI:
- 10.1142/9789814434324_0002
- Bibcode:
- 1989htsr.book...22E