Type-II Superconductors (e.g. YBCO, T_c ≈ 92 K): Below T_c, the Meissner effect expels magnetic flux. But in Type-II, above H_c1, flux penetrates as quantised vortices (flux quanta Φ₀ = h/2e = 2.07×10⁻¹⁵ Wb). Defects in the crystal act as pinning sites — vortices get trapped, creating a strong restoring force. Click the canvas to drag the magnet. The magnet floats because any displacement increases the pinning energy cost.