Magnetic hysteresis measurements are performed on single crystals of Tl2Ba2CuO6+δ superconductors with field parallel to the ab-plane. Our results show anomalously the Bean type critical state behavior with constant critical current in this orientation. The penetration field Hp(T) depends on temperature T according to Hp = Hp (0) [1 - (T/Tc)2, in sharp contrast to Hp(T) with field in the axis c-axis direction. For samples with high transition temperatures, the magnetization undergoes abrupt changes as a function of field at low temperatures. We propose that pinnings on the Josephson vortices in this direction are due to structure defects in these crystals. A local variation in the tunneling distance will introduce a finite pinning on Josephson vortices moving along the ab-plane. The abrupt change in magnetization may be due to field induced decoupling of the Josephson interaction between the layers.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering