All known high-c superconductors are Type-II superconductors. In contrast to Type-I superconductors, which expel all magnetic fields due to the Meissner effect, Type-II superconductors allow magnetic fields to penetrate their interior in quantized units of flux, creating "holes" or "tubes" of normal metallic regions in the superconducting bulk called vortices. Consequently, high-c superconductors can sustain much higher magnetic fields.
all known high-c superconductors are type-ii superconductors in contrast to type-i superconductors which expel all magnetic fields due to the meissner effect type-ii superconductors allow magnetic fields to penetrate their interior in quantized units of flux creating "holes" or "tubes" of normal metallic regions in the superconducting bulk called vortices consequently high-c superconductors can sustain much higher magnetic fields