Holger Motzkau, Thorsten Jacobs, Sven-Olof Katterwe, Andreas Rydh, Vladimir M. Krasnov
Application of a significantly large bias voltage to small Bi2Sr2CaCu2O8+x
mesa structures leads to persistent doping of the mesas. Here we employ this
effect for analysis of the doping dependence of the electronic spectra of
Bi-2212 single crystals by means of intrinsic tunneling spectroscopy. We are
able to controllably and reversibly change the doping state of the same single
crystal from underdoped to overdoped state, without changing its chemical
composition. It is observed that such physical doping is affecting
superconductivity 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 to
progressively more incoherent interlayer tunneling and the pseudogap rapidly
increases, indicative for the presence of the critical doping point. We
distinguish two main mechanisms of persistent electric doping: (i) even in
voltage contribution, attributed to a charge transfer effect, and (ii) odd in
voltage contribution, attributed to reordering of oxygen impurities.
View original:
http://arxiv.org/abs/1202.1665
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