The background magnetic field dependence of the critical current (I c) is studied on magnetic field processed (MFP) Bi2Sr 2CaCu2O8+δ (Bi-2212) multifilamentary tapes in increasing and decreasing magnetic fields. The critical currents are measured in magnetic fields up to 5 T at 4.2 K, with several orientations of the applied magnetic field relative to the tape plane. Two field dependences of Ic are found: a stronger one when the magnetic field is applied perpendicular to the tape plane (B ∥ c) and a weaker one when it is applied parallel to the tape plane (B ⊥ c). The angular dependence of I c as a function of B sin θ, which is the component of the magnetic field perpendicular to the tape plane, exhibits that Ic(B sin θ) coincides with Ic(B ∥ c) in the high-field region, indicating that the tape behaves as a two-dimensional (2D) superconductor. Because of the existence of misalignment in Bi-2212 grains, an average misalignment angle φavg is introduced and is found within the range of 4.5°-6° for the MFP Bi-2212 tape. φavg is independent of the magnetic field, indicating that it is an intrinsic property of the tape. To determine the critical current behaviour for all orientations of the magnetic field, a scaling function f(θ) is introduced. The field-angle dependence of the critical current can be scaled to one curve where the field applied perpendicular to the tape plane at 4.2 K within the field range between 0 and 5 T, both in increasing and decreasing fields, which is of primary importance.
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Condensed Matter Physics
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry