Pseudo-gap features of intrinsic tunneling in (HgBr2)-Bi2212 single crystals

The c-axis tunneling properties of both pristine Bi2212 and its HgBr2 intercalate have been measured in the temperature range 4.2 - 250 K. Lithographically patterned 7-10 unit-cell heigh mesa structures on the surfaces of these single crystals were investigated. Clear SIS-like tunneling curves for current applied in the c-axis direction have been observed. The dynamic conductance dI/dV(V) shows both sharp peaks corresponding to a superconducting gap edge and a dip feature beyond the gap, followed by a wide maximum, which persists up to a room temperature. Shape of the temperature dependence of the c-axis resistance does not change after the intercalation suggesting that a coupling between CuO2-bilayers has little effect on the pseudogap.