Anisotropy in Bi2212 single crystals studied by non-resonant microwave absorption: hysteresis and line shapes

Microwave absorption in a high quality Bi2212 single crystal is studied at 77 K, using non-resonant microwave absorption (NMA) technique. NMA line sha pe and low field hysteresis are highly anisotropic. Two peaks, a narrow P-1 -peak followed by a broad P-2-peak are observed for applied field perpendic ular to the ab-plane. For the applied field parallel to the ab-plane, the b road P-2-peak disappears. For an intermediate orientation of the field, say similar to 55 degrees, to the ab-plane, the P-1-like peak broadens conside rably with a possible mixing of both P-1-peak and P-2-peak. While there is a pronounced hysteresis in the P-1-peak just near zero field for applied fi eld parallel to the ab-plane (Cu-O plane), this hysteresis in P-1-peak is n early absent when the field is applied perpendicular to the ab-plane. In bo th these orientations, hysteresis is absent in NMA signals beyond the P-1-p eak till very high fields. At the intermediate orientation angle of similar to 55 degrees to the ab-plane, the reverse sweep NMA signal collapses into the zero-base line. This is a remarkable hysteresis effect. This may be du e to the interaction between Josephson vortices and Abrikosov vortices whic h can happen in tilted magnetic fields. (C) 2001 Elsevier Science B.V. All rights reserved.