The Anisotropy of Transport Critical Current Densities in Tl2Ba2Ca2Cu3Ox Thin Films under Magnetic Fields up to 20 T

The anisotropy of transport critical current densities (J c) in Tl2Ba2Ca2Cu3O x thin film was measured resistively at 77 K under magnetic fields up to 20 T. When the magnetic field was applied parallel to the a-b plane (a-b plane//B), the values of J c were 1.2×104 and 1.5×103 A/cm2 at 5 and 16 T, respectively. On the other hand, in fields perpendicular to the a-b plane (a-b plane⊥B), J c decreased drastically in the low field region. The irreversible magnetic field (B c2 *) values for (a-b plane//B) and (a-b plane⊥B) were 22.0 and 0.89 T, respectively. The pinning force density (F p=J c×B) can be described by the Kramer scaling law, F p/F p max=3.4×b 1/2(1-b)2, where b (B/B c2 *) is the reduced field. From measuring the angular dependence of J c, as incident angle (θ) increased, J c decreased drastically.