Peak effect and flux pinning in YBa2Cu3O(7-(delta)) single crystals
Abstract
Oxygen annealing studies have been carried out for YBa2Cu3O7-delta single crystals in order to determine the factors controlling the magnetic field dependence of the flux pinning and critical current densities as a function of oxygen content (7-delta). A 300 C anneal removes much of the damage introduced either during crystal growth or by proton irradiation, but it does not permit substantial oxygen uptake to improve the bulk superfluid density. Anneals at 400 C result in substantial oxygen uptake accompanied by an overall enhancement in critical current densities with changes in both the overall superfluid density as well as the pinning effects of oxygen defect clusters. Anneals at 500 and 550 C result in a depletion of oxygen content and a resulting overall diminution of critical current densities. The 'fishtail' shape can be systematically controlled by first adding and then removing oxygen. A model based on the formation and destruction of oxygen point defects and clusters of oxygen defects describes the data rather well.
- Publication:
-
Masters Thesis
- Pub Date:
- February 1995
- Bibcode:
- 1995MsT..........3P
- Keywords:
-
- Crystal Growth;
- Current Density;
- Flux Density;
- Flux Pinning;
- Magnetic Fields;
- Magnetic Flux;
- Point Defects;
- Proton Irradiation;
- Single Crystals;
- Ybco Superconductors;
- Annealing;
- Barium Oxides;
- Copper Oxides;
- Gas Exchange;
- Magnetic Effects;
- Superconductivity;
- Superfluidity;
- Yttrium Oxides;
- Solid-State Physics