Anomalous peak in the superconducting condensate density of cuprate high T c superconductors at a unique critical doping state
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Anomalous peak in the superconducting condensate density of cuprate high T c superconductors at a unique critical doping state Abstract The doping dependence of the superconducting condensate density, n o s , has been studied by muon-spin-rotation for Y 0.8 Ca 0.2 Ba 2 (Cu 1−z Zn z) 3 O 7−δ and Tl 0.5−y Pb 0.5+y Sr 2 Ca 1−x Y x Cu 2 O 7. We find that n o s exhibits a pronounced peak at a unique doping state in the slightly overdoped regime. Its position coincides with the critical doping state where the normal state pseudogap first appears depleting the electronic density of states. A surprising correlation between n o s and the condensation energy U o is observed which suggests unconventional behavior even in the overdoped region. The superconducting condensate density, n s , is proportional to the squared amplitude of the superconducting (SC) order parameter (OP), i.e. of the macroscopic wave function which describes the SC charge carriers. It is thus a fundamental parameter whose variation as a function of temperature (T) and of carrier doping provides important information about the 1
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