Electron Correlation and Impurity-Induced Quasiparticle Resonance States in Cuprate Superconductors

概要

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We theoretically study the quasiparticle resonance states around a nonmagnetic impurity in cuprate superconductors based on t--t'--J--U model. The purpose of introducing the Coulomb repulsive interaction U is to partially impose the double occupancy constraint by employing the Gutzwiller projected mean-field approximation. We determine the spatial variation of the order parameter and the local density of states (LDOS) by self-consistently solving Bogoliubov--de Gennes equations. We find that in the large U limit, a zero-energy resonance peak in the LDOS indeed appears for the impurity potential in the unitary limit, at the same time the asymmetric superconducting coherence peaks are strongly suppressed. As U decreases the electron double occupancy d is permitted and gradually increases, leading to the decreasing of order parameter. In particular the above zero-energy resonance peak begins to evolve into a double-peaked structure since a critical value d_{\text{c}}. These important feathers are qualitatively agreement with the scanning tunneling spectroscopy experiments, and uncover the essential role played by the electron correlation in cuprate superconductors.
The Physical Society of Japanの論文
2013-11-15