Experimental Evidence for Coulomb Charging Effects in the Submicron Bi-2212 Stacks

Abstract

We developed the focused ion beam (FIB) and ion milling techniques for a fabrication of the Bi_2Sr_2CaCu_2O_{8+δ} (Bi-2212) stacked junctions with in-plane size L_{ab} from several microns down to the submicron scale without degradation of T_c. We found that behaviour of submicron junctions (L_{ab} < 1 μm) is quite different from the bigger ones. The critical current density is considerably suppressed, the hysteresis and multibranched structure of the IV characteristics are eliminated, the periodic structure of current peaks reproducibly appears on the IV curves at low temperatures. A period of the structure, ΔV, is consistent with the Coulomb charging energy of a single pair, ΔV = e/C with C the effective capacitance of the stack. We consider this behaviour to originate from the Coulomb blockade of the intrinsic Josephson tunneling in submicron Bi-2212 stacks.