Physical Review Letters

Staggered-field-induced hole pairing in one-dimensional correlated systems

J. Bonča, Peter Prelovšek, Igor Sega, H. Q. Lin, David K Campbell

Published Jul 20, 1992• 16 citations

Abstract

We examine the influence of a staggered magnetic field on states involving a few holes in the one-dimensional t-J and Hubbard models. We apply exact diagonalizations of small systems, an analytical treatment of an anisotropic model, and a high-field perturbation expansion. Our results suggest that even modest staggered fields, h\ensuremath{\ll}t, induce the formation of bound hole pairs in a broad range of parameters, in particular for J/t1 in the t-J model and for U/t>1 in the Hubbard model. In the same regions, by studying the density-density correlations and the compressibility, we argue that many holes form a paired state and that phase separation does not occur.

DOI: 10.1103/physrevlett.69.526

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Physical Review Letters

Staggered-field-induced hole pairing in one-dimensional correlated systems

J. Bonča, Peter Prelovšek, Igor Sega, H. Q. Lin, David K Campbell

Published Jul 20, 1992• 16 citations

Publisher

Abstract

DOI: 10.1103/physrevlett.69.526

Related papers

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Peter Prelovšek, Igor Sega, J. Bonča +2 more

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{\mathit{J}}_{\mathit{c}}

, the phase with paired holes for

{\mathit{J}}_{\mathit{c}}

{\mathit{J}}_{\mathit{s}}

, and the phase separation for J>

{\mathit{J}}_{\mathit{s}}

. Employing for h\ensuremath{\ne}0 the analogy with the universal behavior of one-dimensional interacting fermions within the Luther-Emery regime, we calculate the charge exponent ${\mathit{K}}_{\mathrm{\ensuremath{\rho}}}$, which can be ${\mathit{K}}_{\mathrm{\ensuremath{\rho}}}$>1 in the pairing regime, indicating dominant superconducting fluctuations. An analogous analysis, in particular the perturbation expansion in t/h, performed for the Hubbard t-U-h model shows a phase of stable hole pairs for U

{\mathit{U}}_{\mathit{c}}

. Again ${\mathit{K}}_{\mathrm{\ensuremath{\rho}}}$ seems to approach a nonuniversal value at half-filling.

{\mathit{U}}_{\mathit{c}}

(h). Since under the same conditions we do not find any evidence for stable hole clusters and the phase separation, the latter regime remains a candidate for hole pairing.

{\mathit{J}}_{\mathit{c}}

(n), which obtains an n dependence analogous to the 2D systems, i.e., opposite to the one in the 1D t-J model. The correlation exponent ${\mathit{K}}_{\mathrm{\ensuremath{\rho}}}$ calculated in the Luttinger-liquid regime J

{\mathit{J}}_{\mathit{c}}

(n) indicates also that the region of dominant pairing correlations can move even to J/t1.

The two-dimensional $t\ensuremath{-}J$ model in a staggered field is studied by exact diagonalization of small clusters. For the low-hole-density region and a realistic value of

J/t,

it is found that the presence of a staggered field strengthens the attraction between two holes. With increasing field, the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave superconducting correlations are enhanced while the extended-s-wave ones hardly change. This implies that coexistence of the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave superconducting order and the commensurate antiferromagnetic order occurs in a staggered field.