Charge-Spin Separation and Pairing in a Generalized Hubbard Model
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Starting with the strong-coupling limit of the three-band Hubbard model, we construct an effective field-theory for holes moving in a slowly varying antiferromagnetic (AF) spin-background. The spin degrees of freedom are integrated out within an expansion in generalized Berry-phases. By choosing a spin-quantization axis for the fermions that rotates with the antiferromagnetic order parameter, a gauge theory is obtained where the fermions are minimally coupled to a vector gauge-field, whose fluctuations are controlled by the CP 1 model. As a consequence of the confining potential produced by the U(1) gauge-fields in (2+1) dimensions, bound states result corresponding to charge-spin separation and pairing. An alternative representation in the laboratory reference frame gives a coupling of spin- and fermionic currents that was first obtained by Shraiman and Siggia for the t — J model. The physical content of the gauge-fields is revealed in the global reference frame as chiral spin-fluctuations.
KeywordsReference Frame Hubbard Model Quantum Monte Carlo Global Reference Frame Laboratory Reference Frame
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- J. Zaanen and A.M. Olés, Phys. Rev. B37, 4923 (1988)Google Scholar