Ferroelectric microdomain polaron in YBa2 Cu3O7-δ

The Polaron model based on ferroelectric Ising description of displacement of chain oxygen ions from symmetric position in YBaCuO is offered. The ferroelectric microdomain (FEMD) polaron in antiferroelectric matrix is considered. A discrete procedure of polaron energy minimization is offered. It is shown that the polaron has the changeable intermediate radius, the polaron sizes coincide with experimental ones 10*20Å. Under continuous change of the chain oxygen displacement (an experimental temperature function) the polaron energy at no less then -0,6eV, the form of FEMD and autolocalization potential (narrow well) of hole are found. It is predicted that the FEMD sizes change by jump repolarisation of several dipoles and that the polaron energy can vary strongly below 250K (comparison with experiments) what is accompanied by transfer of carriers between chains and planes. The model permits one to set the correlation between structure experiments and temperature peculiarities of properties of YBaCuO. The classification of peculiarities is proposed. Experimental curve of electrical resistance and occurrence of set of hysteresis loops on temperature dependencies are explained.

Keywords:

• ferroelectric
• domain
• polaron
• HTSC