Field-induced superconductor to insulator transition and phase diagram of Josephson-junction ladders

The superconductor to insulator transition is studied in a self-charging model for a ladder of Josephson-junctions in presence of an external magnetic field. Path integral Monte Carlo simulations of the equivalent (1 + 1)-dimensional classical model are used to study the phase diagram and critical behavior of the field-induced transition. The phase diagram shows an intervening insulating phase separating the (vortex-free) superconducting phase at low fields from the vortex phases at higher fields. A finite-size scaling analysis shows that the field-induced superconducting to insulator transition is in the KT universality class.