New method of studying the anisotropy of lower critical fields in high-T_c superconductors: theory and experiment

摘要

The concepts about the possibility of the studying of anisotropy of the lower critical fields of THSC are developed. The possibility realizes by measuring of H_(c1) values at the turn of textured samples about axe normal to external magnetic field H_(ext) at some turning angle values. The dependence of critical currents I_c of textured samples of HTSC YBa_2Cu_3O_(7-#delta#) (T=77.3K) from intensity of field H_(ext_ with various angles between a direction of a field and researched sample is investigated. On the basis of the received angular dependence I_c(H_(ext)) with the help of the technique, advanced in the present work, the values of the lower critical fields H_(c1) of HTSC YBa_2Cu_3O_(7-#delta#) in a direction of a main axis of orthorhombic lattice and in a perpendicular direction are restored.