Spatial distribution of trapped magnetic flux in Y-Ba-Cu-O superconductors

For the first time, the <> of magnetic field trapped by Y-Ba-Cu-O ceramics from very small to large external magnetic fields was clearly demonstrated. The importance of consideration of spatial distribution of trapped magnetic field, when choosing a model adequately describing remanent magnetization of Y-Ba-Cu-O ceramics in a wide range of external magnetic fields, is shown. It is found that in the range of small fields, H0 ≤ 50 Oe, the magnetization is well described quantitatively by Bean's model and by the uniform magnetization model at H0 ≥ 1 kOe. In the field range 50 Oe , H0< 1 kOe, a smooth transition one is observed from the field of application of one model to that of the other. On the basis of contactless measurements made, the intragranular and intergranular current densities, the pinning forces of Abrikosov and Josephson vortices and estimated. The results obtained agree well with known data. The proximate method is proposed for diagnostics and controllable technology of HTS materials