Persistent electrical doping of Bi2Sr2CaCu2O8+x mesa structures

摘要

Application of a significantly large bias voltage to small Bi2Sr2CaCu2O8+xmesa structures leads to persistent doping of the mesas. Here we employ thiseffect for analysis of the doping dependence of the electronic spectra ofBi-2212 single crystals by means of intrinsic tunneling spectroscopy. We areable to controllably and reversibly change the doping state of the same singlecrystal from underdoped to overdoped state, without changing its chemicalcomposition. It is observed that such physical doping is affectingsuperconductivity in Bi-2212 similar to chemical doping by oxygen impurities:with overdoping the critical temperature and the superconducting gap decrease,with underdoping the c-axis critical current rapidly decreases due toprogressively more incoherent interlayer tunneling and the pseudogap rapidlyincreases, indicative for the presence of the critical doping point. Wedistinguish two main mechanisms of persistent electric doping: (i) even involtage contribution, attributed to a charge transfer effect, and (ii) odd involtage contribution, attributed to reordering of oxygen impurities.