Direct Evidence of Flux Cutting in Type-II Superconductors

A hollow cylinder of a hysteretic type-II superconductor allows applied axial flux to enter the hole smoothly while sustaining trapped azimuthal flux until $H_{c2\mathrm{}}$ is attained showing clearly that flux cutting occurs. A comparison of the evolution of the axial flux, with and without trapped azimuthal flux in the wall, yields data on the energy associated with fluxcutting events. Our technique lends itself to a study of the role of many pertinent parameters in this phenomenon.