2002
DOI: 10.1103/physrevb.66.195102
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Metal-insulator transition and charge ordering in the extended Hubbard model at one-quarter filling

Abstract: We study, with exact diagonalization, the zero temperature properties of the quarter-filled extended Hubbard model on a square lattice. We find that increasing the ratio of the intersite Coulomb repulsion, V, to the bandwidth drives the system from a metal to a charge ordered insulator. The evolution of the optical conductivity spectrum with increasing V is in agreement with the observed optical conductivity of several layered molecular crystals with the and ␤Љ crystal structures. DOI: 10.1103/PhysRevB.66.1951… Show more

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Cited by 44 publications
(54 citation statements)
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“…Table II gives the values obtained for our clusters not only when K is present but also when potassium is completely removed from the system. The 035109-6 [30][31][32]. Moreover, small energy spin excitations such as those included in Table I for doped clusters point to metallic behavior not only because they could approach zero for larger systems but also because they imply charge displacement [33].…”
Section: Many-body Model Hamiltonian a Charge Gapmentioning
confidence: 99%
“…Table II gives the values obtained for our clusters not only when K is present but also when potassium is completely removed from the system. The 035109-6 [30][31][32]. Moreover, small energy spin excitations such as those included in Table I for doped clusters point to metallic behavior not only because they could approach zero for larger systems but also because they imply charge displacement [33].…”
Section: Many-body Model Hamiltonian a Charge Gapmentioning
confidence: 99%
“…A systematic numerical Lanczos ED study was demonstrated by Calandra et al, 125 for cluster sizes up to L = 20. In this case, a powerful method to determine from small systems whether the bulk system is metallic or insulating is to evaluate the Drude weight D.…”
mentioning
confidence: 99%
“…In fact the model contains a transition from a metal to a charge ordered state induced by V , when V = 2t (Ref. 6 ) at zero temperature. Close to the charge ordering transition it is found from exact diagionalization calculations that: (i) the Drude weight is rapidly suppressed; (ii) the optical spectral weight is redistributed so that a net shift from low frequencies into a mid-infrared band occurs; (iii) a characteristic low frequency feature appears in the optical spectra as a consequence of the presence of the strong charge fluctuations occurring in the metallic phase close to the transition.…”
Section: Comparison To Charge Fluctuation Scenariomentioning
confidence: 99%
“…On the other hand, extensive theoretical studies were performed for the electronic correlations in 1/4-filled layered molecular metals close to the charge-order transition 5,6,7,8 . Here we present an optical study of 1/4 filled metals α-(BEDT-TTF) 2 M Hg(SCN) 4 (M =NH 4 ,Rb), aimed on obtaining the effective mass and scattering rate of charge carriers, in order to compare them with theory and to distinguish between the electronic correlations and other factors defining their behavior.…”
Section: Introductionmentioning
confidence: 99%