Dissipative phase transition in a mesoscopic Josephson junction in a weak magnetic field

A dissipative phase transition (DPT) is found in resistively shunted (4-75 k Omega) mesoscopic Josephson junctions owing to suppression of macroscopic quantum tunneling of phase by the interaction with dissipative quantum-mechanical environment. We have studied the behavior of this transition as a function of magnetic field. Instead of a field-induced insulator-superconductor transition, we find a hysteretic insulator-insulator (I-I) transition. The phase diagram for the DPT in a weak magnetic field is outlined. (C) 2000 Elsevier Science B.V. All rights reserved.