Charge solitons in layered superconductors

We studied the interlayer tunneling in Bi-2212 stacks with in plane size variation down to submicron size. For submicron junctions we found experimental evidence of Coulomb charging effcts. The Coulomb blockade leads to the drop down of the Josephson critical current density and to appearance of periodic Coulomb staircase structure of current peaks on the IV characteristics. The period of the structure corresponds to the charge energy of the single Cooper pair charge soliton including the total number of the elementary junctions in the stack (~ 50). We analyzed conditions of the existence of charging effects in layered high-Tc materials of Bi-2212 type