PROPAGATION OF A HOLE ON A NEEL BACKGROUND

Article

关键词: SINGLE-PARTICLE EXCITATIONS;    T-J MODEL;    QUANTUM ANTIFERROMAGNET;    DYNAMICS;    INSULATORS;   

DOI  :  10.1103/PhysRevB.50.9235

来源: SCIE

【 摘 要 】

We analyze the motion of a single hole on a Neel background, neglecting spin fluctuations. Brinkman and Rice studied this problem on a cubic lattice, introducing the retraceable-path approximation for the hole Green's function, exact in a one-dimensional lattice. Metzner et al. showed that the approximation also becomes exact in the infinite-dimensional limit. We tackle this problem by resumming the Nagaoka expansion of the propagator in terms of nonretraceable skeleton paths dressed by retraceable-path insertions. This resummation opens the way to an almost quantitative solution of the problem in all dimensions and, in particular, sheds light on the question of the position of the band edges. We studied the motion of the hole on a double chain and a square lattice, for which deviations from the retraceable-path approximation are expected to be most pronounced. The density of states is mostly adequately accounted for by the retraceable-path approximation. Our band-edge determination points towards an absence of band tails extending to the Nagaoka energy in the spectra of the double chain and the square lattice. We also evaluated the spectral density and the self-energy, exhibiting k dependence due to finite dimensionality. We find good agreement with recent numerical results obtained by Sorella et al. with the Lanczos spectra decoding method. The method we employ enables us to identify the hole paths which are responsible for the various features present in the density of states and the spectral density.

【 授权许可】

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