Josephson-junction arrays with positional disorder: experiments and simulations
Results of a study of Josephson junction arrays with positional disorder are presented, using both experiments and Monte Carlo simulations. The author fabricated 50 x 50 arrays of Pb/Cu proximity-effect junctions, with controlled positional disorder characterized by a parameter ..delta..*. The zero-field resistive transitions of these samples are well described by the Kosterlitz-Thouless-Halperin-Nelson vortex-unbinding theory. Measurements of resistance vs. magnetic field reveal rich structure, with pronounced minima at integer fields, as well as higher-order structure. In samples with disorder, the principal oscillations are found to decay linearly with field, after accounting for the effect of the magnetic field on the critical currents of the individual junctions. Monte Carlo simulations of XY spin systems with positional disorder reveal reentrant behavior in the helicity modulus Y, which is the analog of the effective superfluid density in a junction array, in a narrow range of magnetic fields near the theoretical critical field. As the temperature decreases, Y first increases, then decreases over a narrow temperature range, and finally increases again at low temperatures.
- Research Organization:
- Harvard Univ., Boston, MA (USA)
- OSTI ID:
- 6418810
- Country of Publication:
- United States
- Language:
- English
Similar Records
Positional disorder in Josephson-junction arrays: Experiments and simulations
Phase transition in positionally disordered Josephson-junction arrays in a transverse magnetic field
Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COPPER
CRITICAL CURRENT
CURRENTS
ELECTRIC CURRENTS
ELEMENTS
JOSEPHSON JUNCTIONS
JUNCTIONS
LEAD
METALS
MONTE CARLO METHOD
ORDER-DISORDER TRANSFORMATIONS
OSCILLATIONS
PHASE TRANSFORMATIONS
SUPERCONDUCTING JUNCTIONS
TRANSITION ELEMENTS