Scaling of critical current density in field-aligned grains of (Tl0.75Bi0.25)1.33Sr1.33Ca1.33Cu2 O6.67+δ, the ‘‘1212’’ phase

Abstract
We have measured intragrain critical currents in field‐oriented samples of a rare‐earth‐free high‐Tc superconductor (Tl0.75Bi0.25)1.33Sr1.33Ca1.33Cu2 O6.67+δ, the ‘‘1212’’ phase. The critical current Jc is anisotropic. For fields oriented along the conducting planes, a simple scaling of Jc with field is found. The critical current scales to zero at a field HBc2 (T) which is in good agreement with the form predicted by the flux creep theory.