Angular dependence of the field-cooled, zero-field cooled and remanent magnetization in YBA₂Cu₃O₇ and Bi₂Sr₂CaCu₂O₈ single crystals

We have studied the angular dependence of the zero-field-cooled (M_ZFC), field-cooled (M_FC) and remanent magnetization (M_rem) of YBa₂Cu₃O₇ and Bi₂Sr₂CaCu₂O₈ single crystals, by rotating the crystal relative to the applied field direction. Two compatible mechanisms, namely shape anisotropy and intrinsic anisotropy are used to describe the angular dependence of these quantities. At sufficiently low temperatures, the pinning forces are strong and the relation M_FC=M_ZFC^+M_rem holds for all orientations. The angular dependence of M_ZFC is due only to variation of the demagnetization factor by rotation; whereas the angular dependence of the remanent magnetization can be interpreted by using the two mechanisms. For larger fields or higher temperature the pinning forces are weaker and |M_FC|<|M_ZFC^+Mrem|.