Advances in the criteria for dividing thin superconducting films into narrow and wide films

The results of experimental investigations of the critical currents and certain nonequilibrium phenomena in thin tin films of different width w are analyzed. Ordinarily, thin superconducting films are divided into two groups: narrow channels w <λ_⊥ and wide films w >λ_⊥. A wide transitional region where the condition w >λ_⊥ holds with a large margin and at the same time cannot be explained from the standpoint of the theory of the appearance of a vortex state has been found. This shows that the generally accepted criterion w ∼λ_⊥ for dividing films into wide and narrow does not work. The transition into a wide-film regime, described by the existing theory of the vortex state, is fully completed only for w /λ_⊥(T)>10-20.