Magnetic field profiles of a superconducting strip in an oblique magnetic field

We consider the critical state of a thin superconducting strip in an oblique applied magnetic field H a without any restrictions on the dependence of the critical current density j c on the local magnetic induction B. In such a strip, j c in general is not constant across the thickness of the sample and differs from J c/d, where J c is the critical sheet current. It is shown that in the case of B-dependent j c, the profiles H z(x) of the magnetic-field component perpendicular to the strip plane generally depend on the in-plane component H ax of the applied magnetic field H a. On the basis of this analysis, we explain how one can extract j c(B) from the magnetic-field profiles H z(x) measured by magneto-optical imaging at the upper surface of the strip