Field-induced superconductor-to-insulator transitions in Josephson-junction arrays

H. S. J. van der Zant; F. C. Fritschy; W. J. Elion; L. J. Geerligs; J. E. Mooij

doi:10.1103/PhysRevLett.69.2971

Field-induced superconductor-to-insulator transitions in Josephson-junction arrays

H. S. J. van der Zant, F. C. Fritschy, W. J. Elion, L. J. Geerligs, and J. E. Mooij

Phys. Rev. Lett. 69, 2971 – Published 16 November 1992

Abstract

We have studied phase transitions in fabricated 2D arrays of Josephson junctions where the charging and Josephson coupling energies are about equal. We find a crossover from superconducting behavior in low fields to insulating behavior for fields above a critical value of 0.1–0.2 flux quanta per unit cell. The quantitative aspects agree well with predictions from a recent theory for quantum vortex motion by M. P. A. Fisher and with measurements on films. Similar transitions are found around values f=n/m, where f is the flux per cell and n,m=1,2,3. The field dependence is periodic in f with period 1.