Critical fields for vortex expulsion from narrow superconducting strips

We calculate the critical magnetic fields for vortex expulsion for an infinitely long superconducting strip using the Ginzburg-Landau formalism. Two critical fields associated with the disappearance of either the energetic stability or metastability of vortices in the center of the strip for decreasing magnetic fields can be defined. We compare the theoretical predictions for the critical fields in the London formalism with ours and with recently published experimental results. As expected, for narrow strips, our results better reproduce the experimental findings.