Two-hole problem in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>t</mml:mi></mml:math>-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>J</mml:mi></mml:math>model: A canonical transformation approach

Belinicher, V. I.; Chernyshev, A. L.; Shubin, V. A.

doi:10.1103/physrevb.56.3381

Cited by 53 publications

(57 citation statements)

References 67 publications

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“…Moreover, since the characteristic energy of the bound states found in the t-J models is small, we are skeptical that these states can survive when additional kineticenergy terms are included in the model. Our skepticism is supported by earlier studies 28 and recent numerical data. 34,33 Such conclusions for the pairing problem in t-J-like models drawn from our study create a framework in which it might be necessary to look for d-wave superconductivity unrelated to the Bose condensation of preformed d-wave pairs.…”

Section: Discussionsupporting

confidence: 72%

“…More important conjecture can be made using the results of Ref. 28 and ED data. 33 Since the isotropic dispersion involves a higher kinetic energy, the overall pairing tendency is weakened by these additional hopping terms.…”

Section: ͑45͒mentioning

confidence: 97%

“…The problem with retardation can be solved using a method introduced in Ref. 28. One can assume that ⌫ E (⑀) has no singularities, 29 and therefore the integral over ⑀ 1 in Eq.…”

Section: ͑38͒mentioning

confidence: 99%

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Holes in thet−Jzmodel: A diagrammatic study

Chernyshev¹,

Leung²

1999

Phys. Rev. B

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The t-J z model is the strongly anisotropic limit of the t-J model which captures some general properties of doped antiferromagnets ͑AF's͒. The absence of spin fluctuations simplifies the analytical treatment of hole motion in an AF background, and allows us to calculate single-and two-hole spectra with a high accuracy using a regular diagram technique combined with a real-space approach. At the same time, numerical studies of this model via exact diagonalization on small clusters show negligible finite-size effects for a number of quantities, thus allowing a direct comparison between analytical and numerical results. Both approaches demonstrate that the holes have a tendency to pair in p-and d-wave channels at realistic values of t/J. Interactions leading to pairing and effects selecting p and d waves are thoroughly investigated. The role of transverse spin fluctuations is considered using perturbation theory. Based on the results of the present study, we discuss the pairing problem in the realistic t-J-like model. Possible implications for preformed pairs formation and phase separation are drawn. ͓S0163-1829͑99͒04127-2͔

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Section: Discussionsupporting

confidence: 72%

Section: ͑45͒mentioning

confidence: 97%

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Holes in thet−Jzmodel: A diagrammatic study

Chernyshev¹,

Leung²

1999

Phys. Rev. B

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“…A conclusion which has been drawn from results obtained by means of approaches which originate with the string scenario [29,28,[30][31][32][33][34][35][36][37][38][39][40][41][42] and also from results obtained at the same time by means of exact diagonalizations (EDs) [43][44][45][46][47][48] is that the Fermi surface of hole-doped cuprates, which are doped AF insulators, takes the form of four hole pockets located around points (±π/2, ±π/2). The formation of the hole pockets and of the small Fermi surface which is topologically different from the large conventional Fermi surface seen in overdoped systems has been very recently confirmed [21].…”

Section: Spin Polaron Approachmentioning

confidence: 99%

Spin Polarons in Weakly Doped Antiferromagnets: Experimental Evidence Obtained for Cuprates

2008

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The mechanism of spin polaron formation in moderately doped cuprates is discussed. These objects represent holes embedded into heavy clouds formed by spin fluctuations. Wave functions of spin polarons are spatially confined due to the increase in the exchange energy which is induced by hole motion giving rise to the creation of spin fluctuations. These wave functions are eigenstates of an "unperturbed" Hamiltonian which is defined by processes responsible for the tendency toward confinement. The eigenstates transform according to different irreducible representations of the point group reflecting the symmetry of the problem. Thus, the spin polarons being local wave functions resemble orbital states. The spectrum of optical conductivity in the mid-infrared range is determined by transitions between s-wave and p-wave spin polarons. The hybridization between different spin polarons which is induced by some high order processes gives rise to the formation of energy bands. The pronounced transfer of the spectral weight between different bands is induced by the coupling between spin fluctuations created by the hopping hole and local quantum fluctuations in the empty antiferromagnetic background from which an electron has been rejected, for example during the photoemission process. The form of the energy dispersion for spin polarons gives rise to the formation of a small Fermi surface at the low hole-doping range. These three above mentioned phenomena were observed in cuprates which seems to confirm the spin polaron scenario. The discussion of related experiments is the additional objective of this paper.

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“…Another paper which treated lattice and spin polarons in two dimensions [3], employed a variational approach to compute the wave function of a single polaron from a two-dimensional Hamiltonian. Several other papers treated spin polarons in various ways [4][5][6]. I will summarize our contributions in the use of spin polaron theory to high temperature superconductivity, in this paper.…”

Section: Introductionmentioning

confidence: 99%

The spin polaron theory as a mechanism for high temperature superconductivity

Yanga¹

2017

AIP Conference Proceedings

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Abstract. I summarize in this paper our previous works on the spin polaron theory as a mechanism for high temperature superconductivity in the finite temperature (Matsubara) Green's function method. In this formulation, some bulk thermodynamic properties of high-Tc materials like entropy and specific heat are treated. The hole spectral function is likewise derived. Single-particle tunneling current is calculated for normal metal-superconductor and superconductorsuperconductor junctions. With an effective Hamiltonian derived from this theory, the Josephson tunneling current between two high temperature superconductors is obtained. Current problems like mobility of holes, calculation of energy gap function, the triplet pairing mechanism, among others, are also discussed in this paper, all using the spin polaron formulation.

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Two-hole problem in thet-Jmodel: A canonical transformation approach

Cited by 53 publications

References 67 publications

Holes in thet−Jzmodel: A diagrammatic study

Holes in thet−Jzmodel: A diagrammatic study

Spin Polarons in Weakly Doped Antiferromagnets: Experimental Evidence Obtained for Cuprates

The spin polaron theory as a mechanism for high temperature superconductivity

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