Physics
Type-II superconductors (κ > 1/√2) allow partial flux penetration as quantized vortices. Each carries exactly Φ₀ = h/2e.
κ = λ_L / ξ_GL
fᵢⱼ = (Φ₀²/4πμ₀λ²) K₁(rᵢⱼ/λ)
Vortex repulsion (London interaction) + boundary conditions → Abrikosov triangular lattice minimizes free energy.