Here we examine various aspects of the pairing mechanism for two models, the two-dimensional and two-leg ladder Hubbard models. Both of these models exhibit pairing correlations with d_{x^{2}-y^{2}} symmetry. However, the undoped insulating states of these two systems are different with the two-dimensional lattice characterized by a ground state with long-range antiferromagnetic order and the two-leg ladder having a spin gap in its ground state. Our aim is to gain a better understanding of the underlying pairing mechanism which causes d_{x^{2}-y^{2}} pairing in these two models.Here we examine various aspects of the pairing mechanism for two models, the two-dimensional and two-leg ladder Hubbard models. Both of these models exhibit pairing correlations with d_{x^{2}-y^{2}} symmetry. However, the undoped insulating states of these two systems are different with the two-dimensional lattice characterized by a ground state with long-range antiferromagnetic order and the two-leg ladder having a spin gap in its ground state. Our aim is to gain a better understanding of the underlying pairing mechanism which causes d_{x^{2}-y^{2}} pairing in these two models.

arXiv:cond-mat/9606218TURKISH JOURNAL OF PHYSICSJan 1, 19963 citations

On the nature of pairing in the two-dimensional t–J model

Thomas Maier

Physica B Condensed MatterFeb 15, 20058 citations

Exotic spin, charge and pairing correlations of the two-dimensional doped Hubbard model: A symmetry-entangled mean-field approach

Olivier Juillet, Raymond Frésard

Intertwining of spin, charge, and pairing correlations in the repulsive two-dimensional Hubbard model is shown through unrestricted variational calculations, with projected wave functions free of symmetry breaking. A crossover from incommensurate antiferromagnetism to stripe order naturally emerges in the hole-doped region when increasing the on-site coupling. Although effective attractive pairing interactions are identified, they are strongly fragmented in several modes including $d$ -wave pairing and more exotic channels related to an underlying stripe. We demonstrate that the entanglement of a mean-field wave function by symmetry restoration can largely account for interaction effects, and that our approach is exact for a two-site cluster.Intertwining of spin, charge, and pairing correlations in the repulsive two-dimensional Hubbard model is shown through unrestricted variational calculations, with projected wave functions free of symmetry breaking. A crossover from incommensurate antiferromagnetism to stripe order naturally emerges in the hole-doped region when increasing the on-site coupling. Although effective attractive pairing interactions are identified, they are strongly fragmented in several modes including $d$-wave pairing and more exotic channels related to an underlying stripe. We demonstrate that the entanglement of a mean-field wave function by symmetry restoration can largely account for interaction effects, and that our approach is exact for a two-site cluster.

arXiv:1208.6277Physical Review BMar 25, 201310 citations

Study of spin symmetry in the doped t − J model using infinite projected entangled pair states

Jheng-Wei Li, Benedikt Bruognolo, Andreas Weichselbaum +1 more

We study the two-dimensional $t\text{\ensuremath{-}}J$ model on a square lattice using infinite projected entangled pair states (iPEPS). At small doping, multiple orders, such as antiferromagnetic order, stripe order and superconducting order, are intertwined or compete with each other. We demonstrate the role of spin symmetry at small doping by either imposing SU(2) spin symmetry or its U(1) subgroup in the iPEPS ansatz, thereby excluding or allowing spontaneous spin-symmetry breaking, respectively, in the thermodynamic limit. From a detailed comparison of our simulations, we provide evidence that stripe order is pinned by long-range antiferromagnetic order. We also find SU(2) iPEPS, enforcing a spin-singlet state, yields a uniform charge distribution and favors d-wave singlet pairing.We study the two-dimensional $t\text{\ensuremath{-}}J$ model on a square lattice using infinite projected entangled pair states (iPEPS). At small doping, multiple orders, such as antiferromagnetic order, stripe order and superconducting order, are intertwined or compete with each other. We demonstrate the role of spin symmetry at small doping by either imposing SU(2) spin symmetry or its U(1) subgroup in the iPEPS ansatz, thereby excluding or allowing spontaneous spin-symmetry breaking, respectively, in the thermodynamic limit. From a detailed comparison of our simulations, we provide evidence that stripe order is pinned by long-range antiferromagnetic order. We also find SU(2) iPEPS, enforcing a spin-singlet state, yields a uniform charge distribution and favors d-wave singlet pairing.

arXiv:2006.08323Physical review. B./Physical review. BFeb 15, 202113 citations

d

-wave pairing and more exotic channels related to an underlying stripe. We demonstrate that the entanglement of a mean-field wave function by symmetry restoration can largely account for interaction effects, and that our approach is exact for a two-site cluster.