Spectroscopic Studies of the Phase Transition from the Mott Insulator State to the Charge-Ordering State of κ-(ET)4[M(CN)6][N(C2H5)4]·2H2O (M = CoIII and FeIII) Salts

Łapiński, Andrzej; S̀wietlik, R.; Ouahab, Lahcène; Golhen, Stéphane

doi:10.1021/jp402027x

Cited by 9 publications

(5 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7(f)). Such a CO state with two holes on a single dimer has a large charge gap and would be expected to remain an insulator at low temperatures, as is also found for quasi-1D BCDW-II CTS [34] [325,326,332]. To our knowledge SC has not been observed in any of these κ-(ET) 2 X.…”

Section: κ Ctssupporting

confidence: 53%

See 1 more Smart Citation

From charge- and spin-ordering to superconductivity in the organic charge-transfer solids

Clay,

Mazumdar

2018

Preprint

View full text Add to dashboard Cite

We review recent progress in understanding the different spatial broken symmetries that occur in the normal states of the family of charge-transfer solids (CTS) that exhibit superconductivity (SC), and discuss how this knowledge gives insight to the mechanism of the unconventional SC in these systems. A great variety of spatial broken symmetries occur in the semiconducting states proximate to SC in the CTS, including charge ordering, antiferromagnetism and spin-density wave, spin-Peierls state and the quantum spin liquid. We show that a unified theory of the diverse broken symmetry states necessarily requires explicit incorporation of strong electron-electron interactions and lattice discreteness, and most importantly, the correct bandfilling of one-quarter, as opposed to the effective half-filled band picture that is often employed. Uniquely in the quarter-filled band, there is a very strong tendency to form nearest neighbor spin-singlets, in both one-and two-dimension. The spin-singlet in the quarter-filled band is necessarily charge-disproportionated, with charge-rich pairs of nearest neighbor sites separated by charge-poor pairs of sites in the insulating state. Thus the tendency to spin-singlets, a quantum effect, drives a commensurate charge-order in the correlated quarter-filled band. This charge-ordered spin-singlet, which we label as a paired-electron crystal (PEC), is different from and competes with both the antiferromagnetic (AFM) state and the Wigner crystal (WC) of single electrons. Further, unlike these classical broken symmetries, the PEC is characterized by a spin gap. The tendency to the PEC in two dimension is enhanced by lattice frustration. The concept of the PEC mirrors parallel development of the idea of a density wave of Cooper pairs in the superconducting high T c cuprates, where also the existence of a charge-ordered state in between the antiferromagnetic and the superconducting phase has now been confirmed. Following this characterization of the spatial broken symmetries, we critically reexamine spin-fluctuation and resonating valence bond theories of frustration-driven SC within half-filled band Hubbard and Hubbard-Heisenberg Hamiltonians for the superconducting CTS. We present numerical evidence for the absence of SC within the half-filled band correlated-electron Hamiltonians for any degree of frustration. We then develop a valence-bond theory of SC within which the superconducting state is reached by the destabilization of the PEC by additional pressure-induced lattice frustration that makes the spin-singlets mobile. We present limited but accurate numerical evidence for the existence of such a charge order-SC duality. Our proposed mechanism for SC is the same for CTS in which the proximate semiconducting state is antiferromagnetic instead of charge-ordered, with the only difference that SC in the former is generated via a fluctuating spin-singlet state as opposed to static PEC. In Appendix B we point out that several classes of unconventional superconductors share the same band-fil...

show abstract

Section: κ Ctssupporting

confidence: 53%

“…In some families of κ-(ET) 2 X CO occurs at relatively high temperatures, with the CO pattern consisting of dimers of neutral BEDT-TTF 0 and dimers of BEDT-TTF +1 [325,326], analogous to the CO pattern BCDW-II in 1D (see Fig. 7(f)).…”

Section: κ Ctsmentioning

confidence: 97%

From charge- and spin-ordering to superconductivity in the organic charge-transfer solids

Clay,

Mazumdar

2018

Preprint

View full text Add to dashboard Cite

show abstract

“…Experimentally, κ-Cl and deuterated κ-Br are the only compounds that exhibit AFM 1 , and all other compounds are either ambient pressure superconductors (κ-Br 2 and κ-NCS 2 ), QSL (κ-CN 1 ) or PEC (κ-Hg(SCN) 2 Cl 49 ). Several of the more complicated κ materials such as κ-(ET) 4 69 (M = Co, Fe and Cr) are charge-ordered. Charge-ordering in the last group of materials is accompanied by spin-singlet formation and is apparently driven by strong interdimer coupling 67,68 , which is also the condition for PEC formation 33,34 .…”

Section: Discussionmentioning

confidence: 99%

Coulomb enhancement of superconducting pair-pair correlations in a34-filled model forκ−(BEDT-TTF)2X

Silva¹,

Gomes²,

Mazumdar³

et al. 2016

Phys. Rev. B

View full text Add to dashboard Cite

We present the results of precise correlated-electron calculations on the monomer lattices of the organic charge-transfer solids κ-(BEDT-TTF)2X for 32 and 64 molecular sites. Our calculations are for band parameters corresponding to X = Cu[N(CN)2]Cl and Cu2(CN)3, which are semiconducting antiferromagnetic and quantum spin liquid, respectively, at ambient pressure. We have performed our calculations for variable electron densities ρ per BEDT-TTF molecule, with ρ ranging from 1 to 2. We find that d-wave superconducting pair-pair correlations are enhanced by electron-electron interactions only for a narrow carrier concentration about ρ = 1.5, which is precisely the carrier concentration where superconductivity in the charge-transfer solids occurs. Our results indicate that the enhancement in pair-pair correlations is not related to antiferromagnetic order, but to a proximate hidden spin-singlet state that manifests itself as a charge-ordered state in other chargetransfer solids. Long-range superconducting order does not appear to be present in the purely electronic model, suggesting that electron-phonon interactions also must play a role in a complete theory of superconductivity.

show abstract

“…For a long time, there were only a few compounds reported to exhibit appreciable charge order, such as κ- III , and Cr III ) salts. However, all of them are challenging to grow and limited in crystal size; hence details of their physical properties and electronic states are lacking at the moment [278][279][280].…”

Section: Ferroelectricity Driven By Charge Order In Dimerized Solidsmentioning

confidence: 99%

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Dressel

Tomić

2020

Advances in Physics

View full text Add to dashboard Cite

This review provides a perspective on recent developments and their implications for our understanding of novel quantum phenomena in the physics of two-dimensional organic solids. We concentrate on the phase transitions and collective response in the charge sector, the importance of coupling of electronic and lattice degrees of freedom and stress an intriguing role of disorder. After a brief introduction to low-dimensional organic solids and their crystallographic structures, we focus on the dimensionality and interactions and emergent quantum phenomena. Important topics of current research in organic matter with sizeable electronic correlations are Mott metal-insulator phase transitions, charge order and ferroelectricity. Highly frustrated two-dimensional systems are established model compounds for studying the quantum spin liquid state and the competition with magnetic long-range order. There are also unique examples of quantum disordered state of magnetic and electric dipoles. Representative experimental results are complemented by current theoretical approaches.

show abstract

Spectroscopic Studies of the Phase Transition from the Mott Insulator State to the Charge-Ordering State of κ-(ET)₄[M(CN)₆][N(C₂H₅)₄]·2H₂O (M = Co^III and Fe^III) Salts

Cited by 9 publications

References 74 publications

From charge- and spin-ordering to superconductivity in the organic charge-transfer solids

From charge- and spin-ordering to superconductivity in the organic charge-transfer solids

Coulomb enhancement of superconducting pair-pair correlations in a34-filled model forκ−(BEDT-TTF)2X

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Contact Info

Product

Resources

About