Field cooling memory effect in Bi2212 and Bi2223 single crystals
Abstract
A memory effect in the Josephson vortex system created by magnetic field in the highly anisotropic superconductors Bi2212 and Bi2223 is demonstrated using microwave power absorption. This surprising effect appears despite a very low viscosity of Josephson vortices compared to Abrikosov vortices. The superconductor is field cooled in DC magnetic field Hm oriented parallel to the CuO planes through the critical temperature Tc down to 4K, with subsequent reduction of the field to zero and again above Hm. Large microwave power absorption signal is observed at a magnetic field just above the cooling field clearly indicating a memory effect. The dependence of the signal on deviation of magnetic field from Hm is the same for a wide range of Hm from 0.15T to 1.7T.