Comparison of different ladder models

Jeckelmann, Eric; Scalapino, D. J.; White, Steven R.

doi:10.1103/physrevb.58.9492

Cited by 56 publications

(76 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…RPA calculations for the three-band Hubbard model have also found nematic phases in certain parameter regimes [31][32][33] . Earlier DMRG calculations for a 3-orbital model of a two-leg CuO 2 ladder showed the expected local asymmetric chargetransfer behavior in which doped holes tend to predominantly go on the 2pσ orbitals while doped electrons go on the Cu 3d x 2 −y 2 orbitals 34,35 . These calculations also found d x 2 −y 2 -like pairing correlations for both hole and electron doping in which the near neighbor Cu rung and leg pair-field correlations differ in sign.…”

mentioning

confidence: 99%

Doping asymmetry and striping in a three-orbitalCuO2Hubbard model

White

Scalapino

2015

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

mentioning

confidence: 99%

Doping asymmetry and striping in a three-orbitalCuO2Hubbard model

White

Scalapino

2015

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

“…Likewise, in the t − J model, while J/t can be set to a physical value, one has in effect an infinite onsite Coulomb repulsion arising from the restriction of no double occupancy. The suppression of double occupancy reduces the mobility of the pairs, [17] missing the physics associated with the partial occupation of the O sites surrounding a Cu.…”

mentioning

confidence: 99%

Pairing Correlations ont−U−JLadders

2000

Self Cite

View full text Add to dashboard Cite

Pairing correlations on generalized t-U -J two-leg ladders are reported. We find that the pairing correlations on the usual t-U Hubbard ladder are significantly enhanced by the addition of a nearestneighbor exchange interaction J. Likewise, these correlations are also enhanced for the t-J model when the onsite Coulomb interaction is reduced from infinity. Moreover, the pairing correlations are larger on a t-U -J ladder than on a t-J eff ladder in which J eff has been adjusted so that the two models have the same spin gap at half-filling. This enhancement of the pairing correlations is associated with an increase in the pair-binding energy and the pair mobility in the t-U -J model and point to the importance of the charge transfer nature of the cuprate systems.Various ab initio quantum chemistry calculations as well as model Hamiltonian studies have been used to determine the electronic properties of Cu-oxide clusters.[1-6] In particular, these calculations have provided parameters for simpler, effective one-band Hubbard and t-J models which have then been used to study many-body correlations in larger systems. However, both the oneband Hubbard and the t-J models differ in an essential manner from the high T c cuprates which are known to be charge transfer insulators [7] in their undoped state. Thus, the one-band Hubbard model at half-filling is characterized by a Mott-Hubbard gap which is set by U and in the t-J model, U is taken to infinity with the constraint of no double occupancy. Therefore, while Coulomb fluctuations associated with double occupancy of a site are controlled by U in the Hubbard model, U also determines the strength of the exchange coupling. In the Hubbard model as U increases beyond the bandwidth, J decreases as 4t 2 /U . Although J is an independent parameter in the t-J model, U is infinite in this model, suppressing charge fluctuations.While we believe that the basic pairing mechanism arises from the exchange correlations, the charge transfer nature of the cuprates can play an essential role in the doped systems where it allows for a more flexible arrangement between J and U than reflected in either the one-band Hubbard or t-J models. To explore this, we have carried out density-matrix renormalization group [8] (DMRG) calculations of the pairing correlations on two-leg t-U -J ladders. Ladders are known to provide model systems which exhibit various phenomena similar to those of the cuprates. [9] In particular, when doped away from half-filling they are known to have powerlaw pairing correlations which have opposite, d x 2 −y 2 -like, signs between the rung-rung and rung-leg correlations. These correlations have previously been investigated for both Hubbard [10,11] and t − J models. [12,13] Here we will study a generalized t-U -J model which includes both an onsite Coulomb repulsion U and a nearest neighbor exchange J. While both Hubbard and t-J ladders show pairing correlations when doped, we find that these correlations can be significantly enhanced in a model with both U and J. We argue ...

show abstract

“…Here, we focus on the issue of whether their presence causes any significant changes 11 and in particular whether orbital phases might exist for realistic choices of microscopic interactions, for ␦ 0. 12 We establish, in the weak coupling regime, the phase diagram as a function of hole doping of two-leg ladders whose unit cell contains both Cu and O at- Fig.…”

mentioning

confidence: 99%