Magnetic Field Distribution in a Type II Superconductor

Abstract

Direct measurements of the magnetic field distribution in the gap between half‐ellipsoids of niobium in plastically deformed and annealed states were made using a bismuth thin‐film magnetoresistance probe. An empirical equation of the form r−r₀=C₀B+C₁ (e^C₂B−1) for the field distribution in the deformed sample was found. For the annealed sample, a surface discontinuity of the field was observed, which is a boundary condition for the equilibrium magnetization. Flux jumping was observed when the field was not increased slowly. The distribution in the annealed specimen had reproducible irregularities.