= Superconducting mixed state
The superconducting mixed state is the equilibrium vortex regime of a <type-II superconductor>, between its <lower critical magnetic field> and <upper critical magnetic field> in the ideal bulk description. <Magnetic flux> enters through <Abrikosov vortices>, while the surrounding material retains a nonzero superconducting <order parameter>.
Each vortex has a suppressed-order core and circulating <electric currents>; in the appropriate bulk limit, a singly wound vortex carries one <superconducting flux quantum>. Their mutual interactions can produce an <Abrikosov vortex lattice>. Increasing the field increases the vortex density until superconductivity is destroyed at the upper critical field. Defects can immobilize vortices through <flux pinning>, so a prepared sample's magnetization need not coincide with the equilibrium curve. Spatial coexistence here means vortex cores within superconducting matter, rather than arbitrary macroscopic patches of two phases.<Nobel Lecture: Type-II superconductors and the vortex lattice by Alexei Alexeyevich Abrikosov>[discussion of the vortex solution and triangular lattice]{ref}
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