Abstract
Using the critical state model, the structure of surface flux pinning in a type II superconducting slab of finite thickness is studied. The surface barrier disappears when the external field approaches a superheating field. The flux lines (FLs) metastable state appears when the external field reaches a supercooling field. The critical superheating and the supercooling fields depend on the applied field orientation and the self field generated by a transport current flowing through the slab.