Superconducting gap and pseudogap in Bi2Sr2Ca2Cu3O10+δ by short-pulse interlayer tunneling spectroscopy

Abstract

We have measured the superconducting gap, pseudogap and their doping dependence of CuO2 trilayer high-Tc superconductor Bi2Sr2Ca2Cu3O10+δ by short-pulse interlayer tunneling spectroscopy. While both gaps exhibit temperature dependence similar to those for the bilayer system, their doping dependence behaves differently from that of Tc, presenting an anomalous relationship between Tc and the gap magnitude. In the overdoped region, Tc remains almost unchanged from its optimum value irrespective of doping, while the gap decreases with increasing doping. This is suggestive of inequivalent hole doping in the inner and outer planes, which is thought to occur in trilayer systems.