Quantum regime of Cooper pair tunneling in small-area Bi2Sr2CaCu2O8+delta mesas in magnetic fields

Abstract

We show that application of an c-axis magnetic field decreases the effective interlayer Josephson coupling in small-area Bi2Sr2CaCu2O8+delta (Bi-2212) mesas at low temperatures. As magnetic field increases, the crossover from the classical regime of Cooper pair tunneling to the quantum regime leads to an additional drastic suppression of the Josephson coupling due to the Coulomb blockade. As result, the stack of many intrinsic junctions is nonsuperconducting at high fields. The quantum regime of superconducting tunneling may be reached in mesas with N junctions and area 0.3 mum(2) made of intercalated Bi-2212 crystals by applying c-axis magnetic fields B > 4/N-2 T at N much greater than 1. (C) 2001 Published by Elsevier Science B.V.