Dynamics of holes and universality class of the antiferromagnetic transition in the two-dimensional Hubbard model

Guinea, F.; Louis, E.; Sancho, M. P. López; Vergés, J. A.

doi:10.1016/s0038-1098(99)00525-6

Cited by 5 publications

(1 citation statement)

References 43 publications

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“…It would be interesting to analyze further the experimental implications of this near degeneracy of qualitatively different solutions. Finally, the present method suggests that inhomogeneous spin and charge textures, like stripes or spin polarons, can be viewed as microsocopic manifestations of phase separation, as the natural homogeneous solution which can be obtained in mean field has negative compressibility [34].…”

Section: Figmentioning

confidence: 96%

Partially filled stripes in the two-dimensional Hubbard model: Statics and dynamics

et al. 2001

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The internal structure of stripes in the two dimensional Hubbard model is studied by going beyond the Hartree-Fock approximation. Partially filled stripes, consistent with experimental observations, are stabilized by quantum fluctuations, included through the Configuration Interaction method. Hopping of short regions of the stripes in the transverse direction is comparable to the bare hopping element. The integrated value of n k compares well with experimental results.By now it is well established that charged stripes are formed in a significant doping range of cuprate oxides [1][2][3]. The existence of these stripes was predicted, on the basis of mean field calculations, in advance of its observation, both in the one [4][5][6][7] and the three bands Hubbard model [8]. This is one of the scarce theoretical results in the field of high-T c superconductivity which was confirmed after its prediction. Interest in these calculations decreased, as it was generally understood that the Hartree-Fock approximation was unable to obtain the partially filled stripes observed experimentally. Unrelated calculations found stripes with different fillings in the t-J model [9], and, using different techniques, in the Hubbard model [10], although other numerical calculations show conflicting results [11,12]. Alternatively, it has been argued that stripes in doped Mott antiferromagnets arise from a tendency towards phase separation, frustrated by electrostatic interactions [13,14]. Stripes in the Hubbard model have also been analyzed within slaveboson techniques, which use the Hartree-Fock solutions as input [15].In the present work we show that the mean field calculations, initially used to demonstrate the existence of stripes, can be systematically improved in order to study the partially filled stripes observed experimentally. In addition, they provide significant insight into the internal structure of the stripes and their fluctuations in the transverse direction. The Hartree-Fock method can be considered a quasiclassical approximation to the spin and charge degrees of freedom. Their low amplitude quantum fluctuations can be incorporated by using the Random Phase Approximation [16]. In addition, one needs to consider quantum tunneling processes between degenerate, or nearly degenerate, Hartree-Fock solutions, when there are many. This is achieved with the Configuration Interaction method (CI), widely used in quantum chemistry [17,18]. The combination of the Hartree-Fock and CI methods gives reasonable results even when applied to one dimensional systems [19]. The CI method restores the symmetries broken by the Hartree-Fock approximation, and provides information on the quantum dynamics of the static solutions obtained in mean field, which can be broadly classified into spin polarons or stripes.Previous mean field studies have focused on filled stripes [7], which tend to be the solutions with the lowest energy per hole in this approximation, especially for the values of U/t ∼ 4 used in the initial studies [4][5][6][7]. There are,...

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Section: Figmentioning

confidence: 96%

Partially filled stripes in the two-dimensional Hubbard model: Statics and dynamics

et al. 2001

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Dispersion of ordered stripe phases in the cuprates

Markiewicz

2000

Phys. Rev. B

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A phase separation model is presented for the stripe phase of the cuprates, which allows the doping dependence of the photoemission spectra to be calculated. The idealized limit of a well-ordered array of magnetic and charged stripes is analyzed, including effects of long-range Coulomb repulsion. Remarkably, down to the limit of two-cell wide stripes, the dispersion can be interpreted as essentially a superposition of the two end-phase dispersions, with superposed minigaps associated with the lattice periodicity. The largest minigap falls near the Fermi level; it can be enhanced by proximity to a (bulk) Van Hove singularity. The calculated spectra are dominated by two features -this charge stripe minigap plus the magnetic stripe Hubbard gap. There is a strong correlation between these two features and the experimental photoemission results of a two-peak dispersion in La2−xSrxCuO4, and the peak-dip-hump spectra in Bi2Sr2CaCu2O 8+δ . The differences are suggestive of the role of increasing stripe fluctuations. The 1/8 anomaly is associated with a quantum critical point, here expressed as a percolation-like crossover. A model is proposed for the limiting minority magnetic phase as an isolated two-leg ladder.

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White-Scalapino-like stripes in a mean-field Hubbard model

Kusko¹,

Markiewicz

2001

Phys. Rev. B

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A mean field calculation of the Hubbard model finds a rich phase diagram. The antiferromagnetic phase is generally unstable away from half filling, and there are several regions of phase separation. One solution in particular closely resembles the stripe phase of White and Scalapino. By comparison to unrestricted Hartree-Fock calculations (for which this phase is metastable), it is demonstrated that this phase arises from phase separation. The interface surface tension is found to change sign below a particular stripe width, at which point the stripes begin to meander, gradually crossing over to diagonal.

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Dynamics of holes and universality class of the antiferromagnetic transition in the two-dimensional Hubbard model

Cited by 5 publications

References 43 publications

Partially filled stripes in the two-dimensional Hubbard model: Statics and dynamics

Partially filled stripes in the two-dimensional Hubbard model: Statics and dynamics

Dispersion of ordered stripe phases in the cuprates

White-Scalapino-like stripes in a mean-field Hubbard model

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