Bond-order and charge-density waves in the isotropic interacting two-dimensional quarter-filled band and the insulating state proximate to organic superconductivity

Mazumdar, S.; Clay, R. Torsten; Campbell, David

doi:10.1103/physrevb.62.13400

Cited by 83 publications

(95 citation statements)

References 117 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our principle result is a mapping of the temperature/pressure phase diagram of the SP and CO phases that includes a tetracritical point with a region of coexistence of the two forms of order. There is good agreement between the experiments and the results of calculations on the 1D extended Hubbard 11 and Peierls-Hubbard models 12,13 .…”

supporting

confidence: 70%

Competition and coexistence of bond and charge orders in(TMTTF)2AsF6

et al. 2002

View full text Add to dashboard Cite

(TMTTF)2AsF6 undergoes two phase transitions upon cooling from 300 K. At TCO=103 K a charge-ordering (CO) occurs, and at TSP (B=9 T)=11 K the material undergoes a spin-Peierls (SP) transition. Within the intermediate, CO phase, the charge disproportionation ratio is found to be at least 3:1 from 13 C NMR T −1 1 measurements on spin-labeled samples. Above TSP up to about 3TSP T −1 1 is independent of temperature, indicative of low-dimensional magnetic correlations. With the application of about 0.15 GPa pressure, TSP increases substantially, while TCO is rapidly suppressed, demonstrating that the two orders are competing. The experiments are compared to results obtained from calculations on the 1D extended Peierls-Hubbard model. PACS numbers: 71.20.Rv, 71.30.+h, 71.45.Lr, Inhomogenous charge and spin structures are a consequence of competing interactions and therefore of general interest in correlated electron systems. Examples include the high-T c cuprates 1 and manganites 2 as well as the quasi-2D organic conductors 3 . The quasi-1D salts made from TMTTF or TMTSF molecules are also susceptible to charge-ordered states. Independent of that, they are well-known for the sequence of ground states accessible by applying pressure or selecting different counterions. For example, the material (TMTTF) 2 PF 6 undergoes transitions from spin-Peierls, antiferromagnetic (AF), spin-density wave (SDW), and finally to superconducting (SC) ground states as the pressure is increased to 4-5 GPa 4,5 . For a long time, it was known that another phase transition occurs in a number of TMTTF salts with both centrosymmetric (e.g., AsF 6 , SbF 6 ) and non-centrosymmetric (e.g., ReO 4 ) counterions. Only recently 6,7 was the broken symmetry associated with this transition identified as a charge disproportionation.In TMTTF salts the characteristic temperature of the onset of the charge-ordered (CO) phase is high, on the order of 100 K. It indicates that the interactions driving the CO are relatively strong, and therefore potentially impact the electronic and magnetic properties of the disordered phase. Issues associated with CO correlations in these systems take particular relevance when considering that the nature of the metallic phase of TMTSF salts remains controversial 8,9,10 . Below we report the results of a number of NMR measurements on 13 C spin-labeled samples of (TMTTF) 2 AsF 6 in the CO phase. Our principle result is a mapping of the temperature/pressure phase diagram of the SP and CO phases that includes a tetracritical point with a region of coexistence of the two forms of order. There is good agreement between the experiments and the results of calculations on the 1D extended Hubbard 11 and Peierls-Hubbard models 12,13 .A review of the characteristics of the CO phase and the phase transition is in order. With counterions PF 6 , AsF 6 , and SbF 6 , the ordering temperature is 62 K, 103 K, and 154 K, respectively. Upon cooling, the salts made with the first two are already well into a region of thermally activated resistivitie...

show abstract

supporting

confidence: 70%

Competition and coexistence of bond and charge orders in(TMTTF)2AsF6

et al. 2002

View full text Add to dashboard Cite

show abstract

“…Parameter regime ͑i͒ has been discussed in our previous work. 18,21,25,63 This is the case where the description of the 1 4 -filled band as an effective 1 2 -filled band is appropriate: the unit cell in the 4k F state is a dimer of two sites, and the 2k F transition can be described as the usual SP dimerization of the dimer lattice. We will not discuss this parameter region further.…”

Section: Theoretical Model and Conjecturesmentioning

confidence: 99%

Temperature-driven transition from the Wigner crystal to the bond-charge-density wave in the quasi-one-dimensional quarter-filled band

2007

Self Cite

View full text Add to dashboard Cite

Clay, R. T.; Hardikar, Rahul; and Mazumdar, S., "Temperature-driven transition from the Wigner crystal to the bond-charge-density wave in the quasi-one-dimensional quarter-filled band" Physical Review B / (2007) It is known that within the interacting electron model Hamiltonian for the one-dimensional 1 4 -filled band, the singlet ground state is a Wigner crystal only if the nearest-neighbor electron-electron repulsion is larger than a critical value. We show that this critical nearest-neighbor Coulomb interaction is different for each spin subspace, with the critical value decreasing with increasing spin. As a consequence, with the lowering of temperature, there can occur a transition from a Wigner crystal charge-ordered state to a spin-Peierls state that is a bond-charge-density wave with charge occupancies different from the Wigner crystal. This transition is possible because spin excitations from the spin-Peierls state in the 1 4 -filled band are necessarily accompanied by changes in site charge densities. We apply our theory to the 1 4 -filled band quasi-one-dimensional organic charge-transfer solids, in general, and to 2:1 tetramethyltetrathiafulvalene ͑TMTTF͒ and tetramethyltetraselenafulvalene cationic salts, in particular. We believe that many recent experiments strongly indicate the Wigner crystal to bond-charge-density Wave transition in several members of the TMTTF family. We explain the occurrence of two different antiferromagnetic phases but a single spin-Peierls state in the generic phase diagram for the 2:1 cationic solids. The antiferromagnetic phases can have either the Wigner crystal or the bond-charge-spin-density wave charge occupancies. The spin-Peierls state is always a bond-charge-density wave.

show abstract

“…After the theoretical prediction of the CO ground state for α-(BEDT-TTF) 2 I 3 by Kino and Fukuyama [13], CO in two-dimensional organic compounds was suggested in α-(BEDT-TTF) 2 I 3 [14], and more clearly shown in θ-(BEDT-TTF) 2 RbZn(SCN) 4 [15]. Stimulated by the experimental findings of CO, theoretical studies were conducted on the role of intersite Coulomb interaction in CO [16][17][18], lattice distortion accompanied by CO [19][20][21], the relationship between CO fluctuation and superconductivity (SC) [22], and quantum criticality at the edge of CO [23]. Subsequently, several experimental and theoretical studies have been conducted [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Yakushi

2012

Crystals

View full text Add to dashboard Cite

This paper reviews charge ordering in the organic conductors, β″-(BEDT-TTF) (TCNQ), θ-(BEDT-TTF) 2 X, and α-(BEDT-TTF) 2 X. Here, BEDT-TTF and TCNQ represent bis(ethylenedithio)tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane, respectively. These compounds, all of which have a quarter-filled band, were evaluated using infrared and Raman spectroscopy in addition to optical conductivity measurements. It was found that β″-(BEDT-TTF)(TCNQ) changes continuously from a uniform metal to a chargeordered metal with increasing temperature. Although charge disproportionation was clearly observed, long-range charge order is not realized. Among six θ-type salts, four compounds with a narrow band show the metal-insulator transition. However, they maintain a large amplitude of charge order (Δρ~0.6) in both metallic and insulating phases. In the X = CsZn(SCN) 4 salt with intermediate bandwidth, the amplitude of charge order is very small (Δρ < 0.07) over the whole temperature range. However, fluctuation of charge order is indicated in the Raman spectrum and optical conductivity. No indication of the fluctuation of charge order is found in the wide band X = I 3 salt. In α-(BEDT-TTF) 2 I 3 the amplitude of charge order changes discontinuously from small amplitude at high temperature to large amplitude (Δρ max~0 .6) at low temperature. The long-range chargeordered state shows ferroelectric polarization with fast optical response. The fluctuation of multiple stripes occurs in the high-temperature metallic phase. Among α-(BEDT-TTF) 2 MHg(SCN) 4 (X = NH 4 , K, Rb, Tl), the fluctuation of charge order is indicated only in the X = NH 4 salt. α′-(BEDT-TTF) 2 IBr 2 shows successive phase transitions to the ferroelectric state keeping a large amplitude of charge order (Δρ max~0 .8) over the whole temperature range. It was found that the amplitude and fluctuation of charge order in these compounds is enhanced as the kinetic energy (bandwidth) decreases. OPEN ACCESSCrystals 2012, 2 1292

show abstract

Bond-order and charge-density waves in the isotropic interacting two-dimensional quarter-filled band and the insulating state proximate to organic superconductivity

Cited by 83 publications

References 117 publications

Competition and coexistence of bond and charge orders in(TMTTF)2AsF6

Competition and coexistence of bond and charge orders in(TMTTF)2AsF6

Temperature-driven transition from the Wigner crystal to the bond-charge-density wave in the quasi-one-dimensional quarter-filled band

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Contact Info

Product

Resources

About