Critical current in type-II superconductors near the order-disorder transition

We investigate theoretically the critical states in a long thin superconducting strip with a critical transport current and in a perpendicular magnetic field, which is close to the field of the order-disorder transition in the vortex lattice. In this investigation, the metastable disordered states and the self-magnetic-field of the current are taken into account. Using the obtained results, the dependence of the dc critical current in the strip on the applied magnetic field is found near the order-disorder transition. This dependence can be used to describe the peak effect in low-T_c superconductors and the second magnetization peak in high-T_c superconductors, which occur near this transition. ©2010 The American Physical Society