Effective Hamiltonians for holes in antiferromagnets: a new approach to implement forbidden double occupancy

Apel, W.; Everts, H. U.; Körner, U.

doi:10.1007/s100510050449

Cited by 10 publications

(6 citation statements)

References 17 publications

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“…The one-hole dispersion for J/t = 0.5 calculated here is in quantitative agreement with exact diagonalization (ED) data on a 12-site cluster 14 . The J/t = 10 dispersion curve agrees with recent results which where obtained using the SCBA technique and ED on a 21-site cluster 15 (see Fig. 5).…”

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confidence: 90%

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Spin polarons in triangular antiferromagnets

Vojta

1999

Phys. Rev. B

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The motion of a single hole in a 2D triangular antiferromagnet is investigated using the t-J model. The one-hole states are described by strings of spin deviations around the hole. Using projection technique the one-hole spectral function is calculated. For large J/t we find low-lying quasiparticle-like bands which are well separated from an incoherent background by a gap of order J. However, for small J/t this gap vanishes and the spectrum becomes broad over an energy range of several t. The results are compared with SCBA calculations and numerical data.Comment: 4 pages, 6 figs, to be publish in PR

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confidence: 90%

“…Right: J/|t| = 10, present calculation (solid) together SCBA data (dots) and ED data (21 sites, triangles) from ref. 15 . The energy zero level has been set at the center of mass of the band.…”

mentioning

confidence: 99%

Spin polarons in triangular antiferromagnets

Vojta

1999

Phys. Rev. B

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“…Unlike previous works 18,21 we have performed a detailed description of the whole structures of the spectral function and we were able to trace them back to the two hole motion processes mentioned above. In particular, we have done a careful analysis of quasiparticles, strings, and free hole resonances in the thermodynamic limit.…”

Section: Discussionmentioning

confidence: 99%

“…N is the energy of the localized hole, and E h deloc = E N −1 − E t=0 N −1 is the energy gain due to delocalization of the hole 18 . As the SCBA does not take into account the localized hole energy we have shifted the exact energy spectra by an amount E h loc = −0.5686J for N = 21 in order to make a proper comparison with the SCBA results.…”

Section: A Exact and Scba Comparisonmentioning

confidence: 99%

Quasiparticle vanishing driven by geometrical frustration

2004

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We investigate the single hole dynamics in the triangular t − J model. We study the structure of the hole spectral function, assuming the existence of a 120• magnetic Néel order. Within the self-consistent Born approximation (SCBA) there is a strong momentum and t sign dependence of the spectra, related to the underlying magnetic structure and the particle-hole asymmetry of the model. For positive t, and in the strong coupling regime, we find that the low energy quasiparticle excitations vanish outside the neighbourhood of the magnetic Goldstone modes; while for negative t the quasiparticle excitations are always well defined. In the latter, we also find resonances of magnetic origin whose energies scale as (J/t) 2/3 and can be identified with string excitations. We argue that this complex structure of the spectra is due to the subtle interplay between magnonassisted and free hopping mechanisms. Our predictions are supported by an excellent agreement between the SCBA and the exact results on finite size clusters. We conclude that the conventional quasiparticle picture can be broken by the effect of geometrical magnetic frustration.

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“…In particular, the dynamics of holes in an antiferromagnet have been investigated in great detail in the condensed matter literature [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43]. However, a systematic investigation of these dynamics is complicated due to the strong correlations between the electrons in these systems.…”

Section: Introductionmentioning

confidence: 99%

Two-hole bound states from a systematic low-energy effective field theory for magnons and holes in an antiferromagnet

et al. 2006

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Identifying the correct low-energy effective theory for magnons and holes in an antiferromagnet has remained an open problem for a long time. In analogy to the effective theory for pions and nucleons in QCD, based on a symmetry analysis of Hubbard and t-J-type models, we construct a systematic low-energy effective field theory for magnons and holes located inside pockets centered at lattice momenta (±). The effective theory is based on a nonlinear realization of the spontaneously broken spin symmetry and makes model-independent universal predictions for the entire class of lightly doped antiferromagnetic precursors of high-temperature superconductors. The predictions of the effective theory are exact, order by order in a systematic low-energy expansion. We derive the one-magnon exchange potentials between two holes in an otherwise undoped system. Remarkably, in some cases the corresponding two-hole Schrödinger equations can even be solved analytically. The resulting bound states have d-wave characteristics. The ground state wave function of two holes residing in different hole pockets has a d x 2 −y 2 -like symmetry, while for two holes in the same pocket the symmetry resembles d xy .

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Effective Hamiltonians for holes in antiferromagnets: a new approach to implement forbidden double occupancy

Cited by 10 publications

References 17 publications

Spin polarons in triangular antiferromagnets

Spin polarons in triangular antiferromagnets

Quasiparticle vanishing driven by geometrical frustration

Two-hole bound states from a systematic low-energy effective field theory for magnons and holes in an antiferromagnet

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