Magnetic breakdown in a normal-metal-superconductor proximity sandwich

We study the magnetic response of a clean normal-metal slab of finite thickness in proximity with a bulk superconductor. We determine its free energy and identify two (meta)stable states, a diamagnetic one where the applied field is effectively screened, and a second state, where the field penetrates the normal-metal layer. We present a complete characterization of the first-order transition between the two states which occurs at the breakdown field H-b(T), including its spinodals, the jump in the magnetization, and the latent heat. The bistable regime terminates at a critical temperature T-crit above which the sharp transition is replaced by a continuous crossover. We compare the theory with experiments on normal superconducting cylinders.