70 K hysteretic Josephson effect in mesas patterned on (Bi,Pb)2Sr2CaCu2Oy single crystals

Abstract

We report the engineering of sets of mesas on lead‐substituted single crystals of Bi₂Sr₂CaCu₂O_y. Each mesa behaves as a series array of intrinsic Josephson junctions with, up to 70 K, ‘‘two states’’ hysteretic I(V) characteristics, free of branching, whose R_nIc products can be tuned through geometrical patterning and adjustment of the lead contents. R_nIc values as high as 550 mV at 4.2 K have been reached. The tuning through lead substitution is attributed to the decrease of the anisotropy with increasing lead content.