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Single-particle spectral function of quarter-filled ladder systems

M. Aichhorn·E. Ya. Sherman·H. G. Evertz
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Abstract

We study the single-particle properties of quarter-filled ladder systems such as sodium vanadate by means of a recently developed generalization of the variational cluster perturbation theory to extended Hubbard models. We find a homogeneous antiferromagnetic insulating phase for nearest-neighbor repulsions smaller than a critical value, without any metallic phase for small repulsions. Different from C-DMFT and LDA considerations, the inclusion of diagonal hopping within a ladder has little effect on the bonding bands, while flattening and shifting the antibonding bands. In the low-temperature charge-ordered phase, the spectrum depends on whether the ordering is driven by the Coulomb repulsion or by the coupling to a static lattice distortion. The small change of the experimentally observed gap upon charge ordering implies that the lattice coupling plays an important role in this ordering. Inter-ladder coupling is straightforward to include within our method. We show that it has only a minor effect on the spectral function. The numerically calculated spectra show good agreement with experimental angle-resolved photo-emission data.

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M. Aichhorn, E. Ya. Sherman, H. G. Evertz. 2005-10-20. Single-particle spectral function of quarter-filled ladder systems. https://doi.org/10.1103/physrevb.72.155110

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