COMPARATIVE-STUDY OF AC SUSCEPTIBILITY AND RESISTIVITY OF A SUPERCONDUCTING YBA2CU3O7 SINGLE-CRYSTAL IN A MAGNETIC-FIELD

Results from AC susceptibility chi(H, T) and resistivity rho(H, T) measurements on YBa2Cu3O7 single crystals, in the mixed state by applying magnetic fields H parallel to the c-axis, strongly suggest that the occurrence of the dissipation peak in the imaginary part of the complex susceptibility chi" (omega, T) is due to the skin effect known for electrical transport in metals in the normal state. At fixed field H, the peak temperature Tp(omega, H) increases with increasing frequency of the superimposed AC probing field, and does not coincide with the irreversibility temperature T*(H) < Tp for magnetization obtained in the static limit omega --> 0. A phase diagram is presented which includes the DC irreversibility line H*(T), the peak positions H(p)(omega, T), the experimentally resolved zero-resistivity fields H(rho=0)(T), and the crossover fields from activated to diffuse resistive behavior, H(k)(T), all measured on the same YBa2Cu3O7 single crystal.