title: Magnetic correlations and pairing in the 1/5-depleted square lattice Hubbard model.
abstract: We study the single-orbital Hubbard model on the 1/5-depleted square-lattice geometry, which arises in such diverse systems as the spin-gap magnetic insulator CaV4O9 and ordered-vacancy iron selenides, presenting new issues regarding the origin of both magnetic ordering and superconductivity in these materials. We find a rich phase diagram that includes a plaquette singlet phase, a dimer singlet phase, a Néel and a block-spin antiferromagnetic phase, and stripe phases. Quantum Monte Carlo simulations show that the dominant pairing correlations at half filling change character from d wave in the plaquette phase to extended s wave upon transition to the Néel phase. These findings have intriguing connections to iron-based superconductors, and suggest that some physics of multiorbital systems can be captured by a single-orbital model at different dopings.
authors.affiliation: Department of Physics, University of California, Davis, California 95616, USA and Department of Physics and Astronomy, San Jose State University, San Jose, California 95192, USA.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Khatami
authors.affiliation: Department of Physics, University of California, Davis, California 95616, USA.
authors.forename: Rajiv R P
authors.initials: RR
authors.lastname: Singh
authors.affiliation: Department of Physics, University of California, Davis, California 95616, USA.
authors.forename: Warren E
authors.initials: WE
authors.lastname: Pickett
authors.affiliation: Department of Physics, University of California, Davis, California 95616, USA.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Scalettar