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Yakushi, Kyuya; Yamamoto, Kaoru; Simonyan, Mkhital; Ouyang, J.; Nakano, Chikako; Misaki, Yohji; Tanaka, Kazuyoshi

doi:10.1103/physrevb.66.235102

Cited by 15 publications

(8 citation statements)

References 33 publications

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“…The latter diversity is due to the fact that, in the Q2D compounds, there exists a variety in the anisotropy of transfer integrals originated from different molecular packings, which results in different anisotropic exchange couplings connecting the localized spins when CO is formed: For example, a spin gapped behavior is observed in α-(BEDT-TTF) 2 I 3 45) and 46) due to the alternation in the exchange couplings along the charge rich sites. On the other hand, behavior analogous to our calculation is seen in θ-(BDT-TTP) 2 Cu(NCS) 2 , 47,48) where the ρ(T ) curve shows a rapid increase at around T CO = 250 K, where χ σ (T ) shows no anomaly and below which the system is paramagnetic. In θ-(BEDT-TTF) 2 RbZn(SCN) 4 , where the molecular packing in the 2D plane is the same, χ σ (T ) across T CO = 190 K is also paramagnetic; however, in ρ(T ) a large jump is observed at T = T CO .…”

Section: Summary and Discussionsupporting

confidence: 83%

Finite-Temperature Properties across the Charge Ordering Transition –Combined Bosonization, Renormalization Group, and Numerical Methods–

et al. 2010

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We theoretically describe the charge ordering (CO) metal-insulator transition based on a quasi-onedimensional extended Hubbard model, and investigate the finite temperature (T ) properties across the transition temperature, TCO. In order to calculate T dependence of physical quantities such as the spin susceptibility and the electrical resistivity, both above and below TCO, a theoretical scheme is developed which combines analytical methods with numerical calculations. We take advantage of the renormalization group equations derived from the effective bosonized Hamiltonian, where Lanczos exact diagonalization data are chosen as initial parameters, while the CO order parameter at finite-T is determined by quantum Monte Carlo simulations. The results show that the spin susceptibility does not show a steep singularity at TCO, and it slightly increases compared to the case without CO because of the suppression of the spin velocity. In contrast, the resistivity exhibits a sudden increase at TCO, below which a characteristic T dependence is observed. We also compare our results with experiments on molecular conductors as well as transition metal oxides showing CO.

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Section: Summary and Discussionsupporting

confidence: 83%

Finite-Temperature Properties across the Charge Ordering Transition –Combined Bosonization, Renormalization Group, and Numerical Methods–

et al. 2010

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“…On the other hand, θ-(BDT-TTP) 2 Cu(NCS) 2 having similar structure to the θ-type exhibits a checkerboard type charge order. 36 Thus, the implication of various competing states makes the system complicated and causes interesting physical properties.…”

Section: Discussionmentioning

confidence: 99%

Mean-Field Study of Charge Order with Long Periodicity in θ-(BEDT-TTF)₂X

Kaneko

Ogata

2006

J. Phys. Soc. Jpn.

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Charge ordering phenomenon in θ-(BEDT-TTF)2X is studied by using 1/4-filled extended Hubbard model on an anisotropic triangular lattice through mean-field approximation. It is found that a metallic charge ordered state with 3-periodicity on lattices (3-fold type charge order) is realized in the realistic parameter region where the nearest neighbor Coulomb interaction Vij is nearly isotropic. This 3-fold state survives up to high temperatures by estimating the free energy. Insulating state with diagonal or vertical-type charge ordering appears as increasing anisotropy of Vij. Considering the effect of the structural distortion observed in θ-(BEDT-TTF)2RbZn(SCN)4 at low temperatures, horizontal-type charge ordered insulating phase tends to be stabilized and the region where 3-fold type exists becomes narrower. Our results are consistent with the metallic state with long periodic charge order which can be related to 3-fold type in θ-(BEDT-TTF)2RbZn(SCN)4 at high temperatures and insulating state with horizontal charge order at low temperatures. For θ-(BEDT-TTF)2CsZn(SCN)4, we speculate several kinds of charge-ordered states are energetically competing with each other leading to an inhomogeneous state at low temperatures.

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“…Recent experiments with Raman scattering 33 and optical conductivity measurements 34 on the insulating salt -(BDT-TTP) 2 Cu(NCS) 2 find that the checkerboard chargeordered state discussed in this paper is indeed the ground state. This gives experimental support to the model discussed here.…”

Section: Connection To Experimental Resultsmentioning

confidence: 99%

Dynamical properties of a strongly correlated model for quarter-filled layered organic molecular crystals

et al. 2003

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The dynamical properties of an extended Hubbard model, which is relevant to quarter-filled layered organic molecular crystals, are analyzed. We have computed the dynamical charge correlation function, spectral density, and optical conductivity using Lanczos diagonalization and large-N techniques. As the ratio of the nearestneighbor Coulomb repulsion, V, to the hopping integral, t, increases there is a transition from a metallic phase to a charge-ordered phase. Dynamical properties close to the ordering transition are found to differ from the ones expected in a conventional metal. Large-N calculations display an enhancement of spectral weight at low frequencies as the system is driven closer to the charge-ordering transition in agreement with Lanczos calculations. As V is increased the charge correlation function displays a collective mode which, for wave vectors close to (,), increases in amplitude and softens as the charge-ordering transition is approached. We propose that inelastic x-ray scattering be used to detect this mode. Large-N calculations predict superconductivity with d xy symmetry close to the ordering transition. We find that this is consistent with Lanczos diagonalization calculations, on lattices of 20 sites, which find that the binding energy of two holes becomes negative close to the charge-ordering transition.

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Charge-ordering and magnetic phase transitions inθ−(BDT−TTP)2

Cited by 15 publications

References 33 publications

Finite-Temperature Properties across the Charge Ordering Transition –Combined Bosonization, Renormalization Group, and Numerical Methods–

Finite-Temperature Properties across the Charge Ordering Transition –Combined Bosonization, Renormalization Group, and Numerical Methods–

Mean-Field Study of Charge Order with Long Periodicity in θ-(BEDT-TTF)₂X

Dynamical properties of a strongly correlated model for quarter-filled layered organic molecular crystals

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Charge-ordering and magnetic phase transitions inθ−(BDT−TTP)2

Cited by 15 publications

References 33 publications

Finite-Temperature Properties across the Charge Ordering Transition –Combined Bosonization, Renormalization Group, and Numerical Methods–

Finite-Temperature Properties across the Charge Ordering Transition –Combined Bosonization, Renormalization Group, and Numerical Methods–

Mean-Field Study of Charge Order with Long Periodicity in θ-(BEDT-TTF)2X

Dynamical properties of a strongly correlated model for quarter-filled layered organic molecular crystals

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Product

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Mean-Field Study of Charge Order with Long Periodicity in θ-(BEDT-TTF)₂X