Münster 1999 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 3: Elektronische Eigenschaften von HTSL

TT 3.3: Hauptvortrag

Montag, 22. März 1999, 10:45–11:15, F3

Self-organized charge confinement in cuprate superconductors: effects on the normal- and superconducting state — •Th. Doderer and C.C. Tsuei — IBM Thomas J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598, USA

The well-established observation of the charge stripe formation in the cuprate superconductors is used to explain the most intriguing normal-state properties, namely the pseudogap in the density of states below the temperature T^⋆ and the linearly temperature-dependent in-plane resistivity. The doped holes reside in nanometer-scale grains due to the fragmentation of the stripes, similar as in the case of quantum dots, with intervening anti-ferromagnetic semiconducting/insulating domains. The size of these grains scales with doping. Based on the assumption of charge confinement, we explain quantitatively the temperature- and doping-dependent in-plane resistivity as well as the doping-dependent magnitude of the pseudogap. The charge transport is dominated by one- or two-dimensional diffusion at temperatures above T^⋆, a cross-over to quasi-ballistic transport inside the grains below T^⋆, and eventually variable-range hopping at low temperatures. The pseudogap can be identified with the spectroscopic gap of the quantum dots including the quantum fluctuations of the superconducting order parameter. The intergrain coupling via particle exchange allows a macroscopic phase-coherent superconducting state to establish below the critical temperature T_c. This state can be characterized by Josephson coupling between the three-dimensional array of nano-grains.