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arXiv · 1703.10911

Combined effects of local and nonlocal hybridization on formation and condensation of excitons in the extended Falicov-Kimball model

Pavol Farkasovsky
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Abstract

We study the combined effects of local and nonlocal hybridization on the formation and condensation of the excitonic bound states in the extended Falicov-Kimball model by the density-matrix-renormalization-group (DMRG) method. Analysing the resultant behaviours of the excitonic momentum distribution $N(q)$ we found, that unlike the local hybridization $V$, which supports the formation of the $q=0$ momentum condensate, the nonlocal hybridization $V_n$ supports the formation of the $q=π$ momentum condensate. The combined effect of local and nonlocal hybridization further enhances the excitonic correlations in $q=0$ as well as $q=π$ state, especially for $V$ and $V_n$ values from the charge-density-wave (CDW) region. Strong effects of local and nonlocal hybridization are observed also for other ground-state quantities of the model such as the $f$-electron density, or the density of unbound $d$-electrons, which are generally enhanced with increasing $V$ and $V_n$. The same calculations performed for nonzero values of $f$-level energy $E_f$ revealed that this model can yield a reasonable explanation for the pressure-induced resistivity anomaly observed experimentally in $TmSe_{0.45}Te_{0.55}$ compound.

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Pavol Farkasovsky. 2017-03-31. Combined effects of local and nonlocal hybridization on formation and condensation of excitons in the extended Falicov-Kimball model. https://doi.org/10.1016/j.ssc.2017.03.005

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