Comparative study of AC susceptibility and resistivity of a superconducting YBa 2Cu 3O 7 single crystal in a magnetic field

Abstract

Results from AC susceptibility χ( H,T) and resistivity ϱ( H,T) measurements on YBa 2Cu 3O 7 single crystals, in the mixed state by applying magnetic fields H parallel to the c-axis, strongly suggest that the occurence of the dissipation peak in the imaginary part of the complex susceptibility χ(ω, T) is due to the skin effect known for electrical transport in metals in the normal state. At fixed field H, the peak temperature T p(ω, H) increases with increasing frequency of the superimposed AC probing field, and does not coincide with the irreversibility temperature T ∗( H)< T p for magnetization obtained in the static limit ω→0. A phase diagram is presented which includes the DC irreversibility line H ∗( T), the peak positions H p(ω, T), the experimentally resolved zero-resistivity fields H ϱ =0( T), and the crossover fields from activated to diffuse resistive behavior, H k( T), all measured on the same YBa 2Cu 3O 7 single crystal.