Effects of Short-Range Interactions on Electron-Charge Ordering and Lattice Distortions in the Localized State

Bari, Robert A.

doi:10.1103/physrevb.3.2662

Cited by 150 publications

(72 citation statements)

References 8 publications

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“…[14][15][16], within a framework of a variational approach, and most recently in Ref [17] using the cluster approximation (of BPW-type). In the case of nn repulsion (W > 0) the system can exhibit two types of CDW orderings: C1, inVolving the on-site pairing of electrons (n < 1) or holes (n > 1) (which corresponds to the alternating valence: Km, Km+2 ), and C2, which is the ordering without on-site pairs (Km , Km+1).…”

Section: Charge Orderings For Jjj = Omentioning

confidence: 99%

Pseudospin Models of Superconductors with Very Short Coherence Length

Robaszkiewicz

1994

Acta Phys. Pol. A

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We discuss a few models developed for description of superconductivity with very short coherence length and point out their formal equivalence to specific spin models, such as an anisotropic Heisenberg model (s = 1/2) with two-and four-spin exchange coupling and with fixed magnetization in the z-direction, an XY-Z model with single ion anisotropy and a Kondo-lattice model with anisotropic on-site exchange. New results concerning the phase diagram of the Hubbard model with strong attraction, the electromagnetic properties of systems with the first order superconducting transition and a possibility of local charge moment compensation in systems of coexisting bound pairs and itinerant electrons are presented.

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Section: Charge Orderings For Jjj = Omentioning

confidence: 99%

Pseudospin Models of Superconductors with Very Short Coherence Length

Robaszkiewicz

1994

Acta Phys. Pol. A

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“…For higher V the ground state is a staggered charge-density-wave (CDW), where both the charge and spin excitations are gapped. The transition between the critical SDW and the long-rangeordered CDW has been the subject of numerous studies [3,4,5,6,7,8,9,10,11,12,13,14]. Until recently, it was believed that the SDW-CDW transition occurs for all U > 0 at V > ∼ U/2 and that it is continuous for small U ( < ∼ 5) and first-order for larger U .…”

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confidence: 99%

Ground State Phases of the Half-Filled One-Dimensional Extended Hubbard Model

2004

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Using quantum Monte Carlo simulations, results of a strong-coupling expansion, and Luttinger liquid theory, we determine quantitatively the ground state phase diagram of the one-dimensional extended Hubbard model with on-site and nearest-neighbor repulsions U and V . We show that spin frustration stabilizes a bond-ordered (dimerized) state for U ≈ V /2 up to U/t ≈ 9, where t is the nearest-neighbor hopping. The transition from the dimerized state to the staggered charge-densitywave state for large V /U is continuous for U < ∼ 5.5 and first-order for higher U . The one-dimensional Hubbard model, which describes electrons on a tight-binding chain with single-particle hopping matrix element t and on-site repulsion U , has a charge-excitation gap for any U > 0 at half-filling [1]. In the spin sector, the low-energy spectrum maps onto that of the S = 1/2 Heisenberg chain; the spin coupling J = 4t 2 /U for U → ∞. The spin spectrum is therefore gapless and the spin-spin correlations decay with distance r as (−1) r /r [2]. Hence, the ground state is a quantum critical staggered spin-density-wave (SDW). In the simplest extended Hubbard model, a nearest-neighbor repulsion V is also included. The Hamiltonian is, in standard notation and with t = 1 hereafter,The low-energy properties for V < ∼ U/2 are similar to those at V = 0. For higher V the ground state is a staggered charge-density-wave (CDW), where both the charge and spin excitations are gapped. The transition between the critical SDW and the long-rangeordered CDW has been the subject of numerous studies [3,4,5,6,7,8,9,10,11,12,13,14]. Until recently, it was believed that the SDW-CDW transition occurs for all U > 0 at V > ∼ U/2 and that it is continuous for small U ( < ∼ 5) and first-order for larger U . However, based on a study of excitation spectra of small chains, Nakamura argued that there is also a bond-order-wave (BOW) phase [10], where the ground state has a staggered modulation of the kinetic energy density (dimerization), in a narrow region between the SDW and CDW phases for U smaller than the value at which the transition changes to first order. Previous studies [6,7,8,9] had indicated an SDW state in this region. Nakamura's BOW-CDW boundary coincides with the previously determined SDW-CDW boundary. The presence of dimerization and the accompanying spin gap were subsequently confirmed using quantum Monte Carlo (QMC) simulations [11,12]. The BOW phase now also has a weak-coupling theory [13].The existence of an extended BOW phase has recently been disputed. Jeckelmann argued, on the basis of density-matrix-renormalization-group (DMRG) calculations, that the BOW exists only on a short segment of the first-order part of the SDW-CDW boundary [14], i.e., that the transition always is SDW-CDW and that BOW order is only induced on part of the coexistence curve. However, QMC calculations demonstrate the existence of BOW order well away from the phase boundary [12].Although several studies agree on the existence of an extended BOW phase [10,11,12,13], the shape of ...

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“…(3)(4)(5)(6)(7)(8). It suffices to consider the simplest conceivable cluster, namely two nearest-neighbour sites i and j, defining …”

Section: Resultsmentioning

confidence: 99%

“…(1) below). The atomic limit (zero band width) was treated by Bari [5] who determined the ground states exactly for equal numbers of electrons and lattice sites and found a "Mott state" with one electron at each lattice site and a charge ordered state with vacant and doubly occupied sites in an alternating fashion. Bari also investigated a possible phase transition by a mean-field approximation.…”

Section: Introductionmentioning

confidence: 99%

Ground states of extended Hubbard models in the atomic limit

Brandt

Stolze

1986

Z. Physik B - Condensed Matter

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The possible ground states of an extended Hubbard model in the atomic limit, augmented by an additional nearest neighbour Ising-like interaction and an external magnetic field, are rigorously determined for arbitrary values of the coupling parameters and arbitrary chemical potential. The method used requires only simple convexity arguments and the examination of all possible configurations of small clusters of lattice sites, which may be done by computer. The results are valid for all lattices of AB type (two interpenetrating sublattices). The types of order found are ferromagnetic, antiferromagnetic, and charge density wave. Perturbation theory suggests that for finite band width there may be a state showing both a charge density wave and ferromagnetic order.

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Effects of Short-Range Interactions on Electron-Charge Ordering and Lattice Distortions in the Localized State

Cited by 150 publications

References 8 publications

Pseudospin Models of Superconductors with Very Short Coherence Length

Pseudospin Models of Superconductors with Very Short Coherence Length

Ground State Phases of the Half-Filled One-Dimensional Extended Hubbard Model

Ground states of extended Hubbard models in the atomic limit

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