We study the two-dimensional Hubbard model with nonmagnetic Zn impurities modeled by binary diagonal disorder using Quantum Monte Carlo within the Dynamical Cluster Approximation. With increasing Zn content we find a strong suppression of d-wave superconductivity concomitant to a reduction of antiferromagnetic spin fluctuations. $T_c$ vanishes linearly with Zn impurity concentration. The spin susceptibility changes from pseudogap to Curie-Weiss like behavior indicating the existence of free magnetic moments in the Zn doped system. We interpret these results within the RVB picture.We study the two-dimensional Hubbard model with nonmagnetic Zn impurities modeled by binary diagonal disorder using Quantum Monte Carlo within the Dynamical Cluster Approximation. With increasing Zn content we find a strong suppression of d-wave superconductivity concomitant to a reduction of antiferromagnetic spin fluctuations. $T_c$ vanishes linearly with Zn impurity concentration. The spin susceptibility changes from pseudogap to Curie-Weiss like behavior indicating the existence of free magnetic moments in the Zn doped system. We interpret these results within the RVB picture.

arXiv:cond-mat/0201037Jan 3, 20020 citations

Band Kondo Effect in the Doped 2D Hubbard Model

Bumsoo Kyung

We present strong numerical evidence for the band Kondo effect in the doped 2D Hubbard model by showing the systematic change of the density of states, imaginary part of the self-energy, effective magnetic moment and quasiparticle residue upon decreasing the temperature. Quadratically vanishing (in frequency) scattering rates near the Fermi energy and a linearly vanishing (in temperature) effective magnetic moment at low temperatures strongly support the screening of magnetic moments from singly occupied electrons by doped holes in the 2D Hubbard model.We present strong numerical evidence for the band Kondo effect in the doped 2D Hubbard model by showing the systematic change of the density of states, imaginary part of the self-energy, effective magnetic moment and quasiparticle residue upon decreasing the temperature. Quadratically vanishing (in frequency) scattering rates near the Fermi energy and a linearly vanishing (in temperature) effective magnetic moment at low temperatures strongly support the screening of magnetic moments from singly occupied electrons by doped holes in the 2D Hubbard model.

arXiv:cond-mat/9802250Feb 24, 19980 citations

Superconductivity of the 2D Hubbard Model with a Small U

淳近藤

電子技術総合研究所彙報Nov 1, 20001 citation

Impurity effects on dx2−y2 -wave superconducting state in strongly correlated Hubbard model

Ryo Sato, Hisatoshi Yokoyama

Abstract With cuprate superconductors in mind, we study the effects of point-type impurity potential (V) on a d x 2−y 2 -wave superconducting (d-SC) state in a strongly correlated squarelattice Hubbard model (U/t = 12) with a diagonal transfer (t′), using a variational Monte Carlo method. At half filling, insulator-to-conductor (filling-control-type Mott) transitions occur at <?CDATA $V={V}_{U}^{(\pm )}\sim \pm U$ ?> V = V U ( ± ) ∼ ± U . The phase realized for <?CDATA $V\lt {V}_{U}^{(-)}$ ?> V < V U ( − ) is robust d-SC and the charge carriers are holes, whereas for <?CDATA $V\gt {V}_{U}^{(+)}$ ?> V > V U ( + ) a metallic (or weak d-SC) state appears with charge carriers of electrons. For a partially-filled case where the impurity density is equal to the doping rate, a d-SC-to-insulator transition arises at V ≡ V M ∼ 4t. In the weak-|V| phases, the impurity effects in the electron distribution are smeared out by the screening effect, whereas in the strong-|V| phases, the electron distribution directly depend on the impurity configurations.Abstract With cuprate superconductors in mind, we study the effects of point-type impurity potential (V) on a d x 2−y 2 -wave superconducting (d-SC) state in a strongly correlated squarelattice Hubbard model (U/t = 12) with a diagonal transfer (t′), using a variational Monte Carlo method. At half filling, insulator-to-conductor (filling-control-type Mott) transitions occur at <?CDATA $V={V}_{U}^{(\pm )}\sim \pm U$?> V = V U ( ± ) ∼ ± U . The phase realized for <?CDATA $V\lt {V}_{U}^{(-)}$?> V < V U ( − ) is robust d-SC and the charge carriers are holes, whereas for <?CDATA $V\gt {V}_{U}^{(+)}$?> V > V U ( + ) a metallic (or weak d-SC) state appears with charge carriers of electrons. For a partially-filled case where the impurity density is equal to the doping rate, a d-SC-to-insulator transition arises at V ≡ V M ∼ 4t. In the weak-|V| phases, the impurity effects in the electron distribution are smeared out by the screening effect, whereas in the strong-|V| phases, the electron distribution directly depend on the impurity configurations.

Journal of Physics Conference SeriesSep 1, 20190 citations

Superconductivity in the Two-Dimensional Hubbard Model

Walter Metzner

Foundations of PhysicsDec 1, 20001 citation

T_c

vanishes linearly with Zn impurity concentration. The spin susceptibility changes from pseudogap to Curie-Weiss like behavior indicating the existence of free magnetic moments in the Zn doped system. We interpret these results within the RVB picture.

V={V}_{U}^{(\pm )}\sim \pm U

?> V = V U ( ± ) ∼ ± U . The phase realized for <?CDATA

V\lt {V}_{U}^{(-)}

?> V < V U ( − ) is robust d-SC and the charge carriers are holes, whereas for <?CDATA

V\gt {V}_{U}^{(+)}

?> V > V U ( + ) a metallic (or weak d-SC) state appears with charge carriers of electrons. For a partially-filled case where the impurity density is equal to the doping rate, a d-SC-to-insulator transition arises at V ≡ V M ∼ 4t. In the weak-|V| phases, the impurity effects in the electron distribution are smeared out by the screening effect, whereas in the strong-|V| phases, the electron distribution directly depend on the impurity configurations.