The recent discovery of superconductivity under high pressure in the ladder compound ${\mathrm{BaFe}}_{2}{\mathrm{S}}_{3}$ has opened a new field of research in iron-based superconductors with focus on quasi-one-dimensional geometries. In this publication, using the density matrix renormalization group technique, we study a two-orbital Hubbard model defined in one-dimensional chains. Our main result is the presence of hole binding tendencies at intermediate Hubbard $U$ repulsion and robust Hund coupling ${J}_{H}/U=0.25$ . Binding does not occur either in weak coupling or at very strong coupling. The pair-pair correlations that are dominant near half-filling, or of similar strength as the charge and spin correlation channels, involve hole-pair operators that are spin singlets, use nearest-neighbor sites, and employ different orbitals for each hole. The Hund coupling strength, presence of robust magnetic moments, and antiferromagnetic correlations among them are important for the binding tendencies found here.The recent discovery of superconductivity under high pressure in the ladder compound ${\mathrm{BaFe}}_{2}{\mathrm{S}}_{3}$ has opened a new field of research in iron-based superconductors with focus on quasi-one-dimensional geometries. In this publication, using the density matrix renormalization group technique, we study a two-orbital Hubbard model defined in one-dimensional chains. Our main result is the presence of hole binding tendencies at intermediate Hubbard $U$ repulsion and robust Hund coupling ${J}_{H}/U=0.25$. Binding does not occur either in weak coupling or at very strong coupling. The pair-pair correlations that are dominant near half-filling, or of similar strength as the charge and spin correlation channels, involve hole-pair operators that are spin singlets, use nearest-neighbor sites, and employ different orbitals for each hole. The Hund coupling strength, presence of robust magnetic moments, and antiferromagnetic correlations among them are important for the binding tendencies found here.

arXiv:1705.08780Physical review. B./Physical review. BJul 31, 201730 citations

Hole pairing in an extended Hubbard model

J. H. Jefferson

Physica B Condensed MatterApr 1, 19902 citations

Sign change of the extended s -wave pairing vertex in the dynamic Hubbard model: A quantum Monte Carlo study

Karim Bouadim, Matthew Enjalran, F. Hébert +2 more

The ``dynamic'' Hubbard Hamiltonian describes interacting fermions on a lattice whose on-site repulsion is modulated by a coupling to a fluctuating bosonic field. We investigate one such model, introduced by Hirsch, using the determinant quantum Monte Carlo method. Our key result is that the extended $s$ -wave pairing vertex, repulsive in the usual static Hubbard model, becomes attractive as the coupling to the fluctuating Bose field increases. The sign problem prevents us from exploring a low enough temperature to see if a superconducting transition occurs. We also observe a stabilization of antiferromagnetic correlations and the Mott gap near half-filling, and a near linear behavior of the energy as a function of particle density which indicates a tendency toward phase separation.The ``dynamic'' Hubbard Hamiltonian describes interacting fermions on a lattice whose on-site repulsion is modulated by a coupling to a fluctuating bosonic field. We investigate one such model, introduced by Hirsch, using the determinant quantum Monte Carlo method. Our key result is that the extended $s$-wave pairing vertex, repulsive in the usual static Hubbard model, becomes attractive as the coupling to the fluctuating Bose field increases. The sign problem prevents us from exploring a low enough temperature to see if a superconducting transition occurs. We also observe a stabilization of antiferromagnetic correlations and the Mott gap near half-filling, and a near linear behavior of the energy as a function of particle density which indicates a tendency toward phase separation.

arXiv:0710.1356Physical Review BJan 22, 20089 citations

Hole pairing in the Hubbard model

Luis Antonio Pérez, C. Wang

Journal of Magnetism and Magnetic MaterialsJan 1, 19981 citation

Electronic structure, magnetic properties, and pairing tendencies of the copper-based honeycomb lattice Na2Cu2TeO6

Ling-Fang Lin, Rahul Soni, Yang Zhang +6 more

Spin-1/2 chains with alternating antiferromagnetic (AFM) and ferromagnetic (FM) couplings have attracted considerable interest due to the topological character of their spin excitations. Here, using density functional theory and density-matrix renormalization-group (DMRG) methods, we have systematically studied the dimerized chain system ${\mathrm{Na}}_{2}{\mathrm{Cu}}_{2}{\mathrm{TeO}}_{6}$ with a ${d}^{9}$ electronic configuration. Near the Fermi level, in the nonmagnetic phase the dominant states are mainly contributed by the Cu $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbitals highly hybridized with the O $2p$ orbitals, leading to an ``effective'' single-orbital low-energy model. By calculating the relevant hoping amplitudes, we explain the size and sign of the exchange interactions in ${\mathrm{Na}}_{2}{\mathrm{Cu}}_{2}{\mathrm{TeO}}_{6}$ . In addition, a single-orbital Hubbard model is constructed for this dimerized chain system where the quantum fluctuations are taken into account. Both AFM and FM couplings (leading to an $\ensuremath{\uparrow}\text{\ensuremath{-}}\ensuremath{\downarrow}\text{\ensuremath{-}}\ensuremath{\downarrow}\text{\ensuremath{-}}\ensuremath{\uparrow}$ state) along the chain were found in our DMRG and Lanczos calculations, in agreement with density functional theory and neutron-scattering results. The hole pairing binding energy $\mathrm{\ensuremath{\Delta}}E$ is predicted to be negative at Hubbard $U\ensuremath{\sim}11\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$, suggesting incipient pairing tendencies.Spin-1/2 chains with alternating antiferromagnetic (AFM) and ferromagnetic (FM) couplings have attracted considerable interest due to the topological character of their spin excitations. Here, using density functional theory and density-matrix renormalization-group (DMRG) methods, we have systematically studied the dimerized chain system ${\mathrm{Na}}_{2}{\mathrm{Cu}}_{2}{\mathrm{TeO}}_{6}$ with a ${d}^{9}$ electronic configuration. Near the Fermi level, in the nonmagnetic phase the dominant states are mainly contributed by the Cu $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbitals highly hybridized with the O $2p$ orbitals, leading to an ``effective'' single-orbital low-energy model. By calculating the relevant hoping amplitudes, we explain the size and sign of the exchange interactions in ${\mathrm{Na}}_{2}{\mathrm{Cu}}_{2}{\mathrm{TeO}}_{6}$. In addition, a single-orbital Hubbard model is constructed for this dimerized chain system where the quantum fluctuations are taken into account. Both AFM and FM couplings (leading to an $\ensuremath{\uparrow}\text{\ensuremath{-}}\ensuremath{\downarrow}\text{\ensuremath{-}}\ensuremath{\downarrow}\text{\ensuremath{-}}\ensuremath{\uparrow}$ state) along the chain were found in our DMRG and Lanczos calculations, in agreement with density functional theory and neutron-scattering results. The hole pairing binding energy $\mathrm{\ensuremath{\Delta}}E$ is predicted to be negative at Hubbard $U\ensuremath{\sim}11\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$, suggesting incipient pairing tendencies.

arXiv:2204.01688Physical review. B./Physical review. BJun 10, 20226 citations

The recent discovery of superconductivity under high pressure in the ladder compound

{\mathrm{BaFe}}_{2}{\mathrm{S}}_{3}

has opened a new field of research in iron-based superconductors with focus on quasi-one-dimensional geometries. In this publication, using the density matrix renormalization group technique, we study a two-orbital Hubbard model defined in one-dimensional chains. Our main result is the presence of hole binding tendencies at intermediate Hubbard

U

repulsion and robust Hund coupling

{J}_{H}/U=0.25

. Binding does not occur either in weak coupling or at very strong coupling. The pair-pair correlations that are dominant near half-filling, or of similar strength as the charge and spin correlation channels, involve hole-pair operators that are spin singlets, use nearest-neighbor sites, and employ different orbitals for each hole. The Hund coupling strength, presence of robust magnetic moments, and antiferromagnetic correlations among them are important for the binding tendencies found here.

s

-wave pairing vertex, repulsive in the usual static Hubbard model, becomes attractive as the coupling to the fluctuating Bose field increases. The sign problem prevents us from exploring a low enough temperature to see if a superconducting transition occurs. We also observe a stabilization of antiferromagnetic correlations and the Mott gap near half-filling, and a near linear behavior of the energy as a function of particle density which indicates a tendency toward phase separation.

{\mathrm{Na}}_{2}{\mathrm{Cu}}_{2}{\mathrm{TeO}}_{6}

with a

{d}^{9}

electronic configuration. Near the Fermi level, in the nonmagnetic phase the dominant states are mainly contributed by the Cu $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbitals highly hybridized with the O

2p

orbitals, leading to an ``effective'' single-orbital low-energy model. By calculating the relevant hoping amplitudes, we explain the size and sign of the exchange interactions in

{\mathrm{Na}}_{2}{\mathrm{Cu}}_{2}{\mathrm{TeO}}_{6}

. In addition, a single-orbital Hubbard model is constructed for this dimerized chain system where the quantum fluctuations are taken into account. Both AFM and FM couplings (leading to an $\ensuremath{\uparrow}\text{\ensuremath{-}}\ensuremath{\downarrow}\text{\ensuremath{-}}\ensuremath{\downarrow}\text{\ensuremath{-}}\ensuremath{\uparrow}$ state) along the chain were found in our DMRG and Lanczos calculations, in agreement with density functional theory and neutron-scattering results. The hole pairing binding energy $\mathrm{\ensuremath{\Delta}}E$ is predicted to be negative at Hubbard $U\ensuremath{\sim}11\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$, suggesting incipient pairing tendencies.