Strong granularity-correlated and intragrain modulations of the superconducting order parameter are demonstrated in heavily boron-doped diamond situated not yet in the vicinity of the metal-insulator transition. These modulations at the superconducting state (SC) and at the global normal state (NS) above the resistive superconducting transition, reveal that local Cooper pairing sets in prior to the global phase coherence.

The quanum levels and corresponding vortex states in nanoscale superconductors are investigated within generalized Bogolubov-de Gennes theory. For symmetric (squareshaped) samples thermodynamically stable vortex phases form symmetry-consistent patterns and no transition to conventional Abrikosov-like vortex patterns occurs till T=0K for sizes not exceeding 25 nm. For vorticity L = 2 a giant vortex is stabilized at temperatures in the vicinity of T c , which transforms into a giant antivortex L = −2 and four normal vortices with lowering the temperature. On the other hand, the vortex pattern for vorticity L = 3 corresponds to an antivortex L = −1 and four normal vortices in the whole temperature domain.

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