Extremely correlated Fermi liquids: The formalism

Article

关键词: VALENCE BOND STATE;    SUPERCONDUCTIVITY;    ENERGY;   

DOI  :  10.1103/PhysRevB.87.125124

来源: SCIE

【 摘 要 】

We present the detailed formalism of the extremely correlated Fermi liquid theory, developed for treating the physics of the t-J model. We start from the exact Schwinger equation of motion for the Green's function for projected electrons, and develop a systematic expansion in a parameter., relating to the double occupancy. The resulting Green's function has a canonical part arising from an effective Hamiltonian of the auxiliary electrons, and a caparison part playing the role of a frequency-dependent adaptive spectral weight. This adaptive weight balances the requirement at low omega of the invariance of the Fermi volume, and at high omega of decaying as c(0)/i(omega), with a correlation-depleted c(0) < 1. The effective Hamiltonian H-eff describing the auxiliary fermions is given a natural interpretation with an effective interaction V-eff containing both the exchange J(ij) and the hopping parameters t(ij). It is made Hermitian by adding suitable terms that ultimately vanish, in the symmetrized theory developed in this paper. Simple but important shift invariances of the t-J model are noted with respect to translating its parameters uniformly. These play a crucial role in constraining the form of Veff and also provide checks for further approximations. The auxiliary and physical Green's function satisfy two sum rules, and the Lagrange multipliers for these are identified. A complete set of expressions for the Green's functions to second order lambda is given, satisfying various invariances. A systematic iterative procedure for higher order approximations is detailed. A superconducting instability of the theory is noted at the simplest level with a high transition temperature.

【 授权许可】

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