Fizika Nizkikh Temperatur: Volume 27, Number 9-10 (September 2001), p. 1019-1029    ( to contents , go back )

Commensurable vortex lattices in V thin films and superconducting V/Si superlattices

N. Ya. Fogel, E. I. Buchstab

Department of Physics, Solid State Institute, Technion, Haifa 32100, Israel

V. G. Cherkasova, O. I. Yuzephovich, M. Yu. Mikhailov

B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine

and A. N. Stetzenko

National Technical University "Kharkov Polytechnical institute", Frunze st. 21, 61002 Kharkov, Ukraine
pos Анотація:

Received March 21, 2001

Abstract

The peculiarities of the mixed phase are investigated in type II superconducting thin films in a parallel to the film surface magnetic field. The measurements of nonmonotonous dependences of critical current Ic on magnetic field H|| allow the commensurable vortex lattices with a different number of vortex chains in the film to be revealed. It is established that the effect of commensurability between vortex lattice parameter and film thickness is possibile in homogeneous films only for ideal film boundaries which allow for the formation of an infinite vortex√vortex image lattice. The deterioration of the surface smoothness and the disruption of the parallelism of the film surfaces cause disappearing of oscillations Ic and sharp decreasing of the critical current. The lock-in transition conditioned by the influence of surface barrier is observed for the first time on thin films. It is established that too different commensurability effects are observed simutaneously in the thin layered samples. One of them is the commensurability effect between the vortex lattice parameter and the period of layering and the other between the vortex lattice parameter and the total sample thickness. The H-T phase diagram of the homogeneous film in a parallel magnetic field is considered.

PACS:
74.60.Ec -
74.60.Ge -
74.76.-w -
74.80.Dm -
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