Effect of Included Guest Molecules on the Normal State Conductivity and Superconductivity of β‘ ‘-(ET)4[(H3O)Ga(C2O4)3]·G (G = Pyridine, Nitrobenzene)

Akutsu, Hiroki; Akutsu-Sato, A; Turner, Scott S.; Pevelen, Delphine D. Le; Day, Peter; Laukhin,; Klehe, AK; Singleton, John; Tocher, Derek A.; Probert, Michael R.; Howard, JA

doi:10.1021/ja0273849

Cited by 90 publications

(107 citation statements)

References 5 publications

(7 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ␤Љ-͑BEDT-TTF͒ 4 ͓͑H 3 O͒M͑C 2 O 4 ͒ 3 ͔ · Y samples were grown using electrocrystallisation techniques as described elsewhere; 14,[16][17][18] they are generally ϳ3 ϫ 1 ϫ 0.5 mm 3 needles. It is possible to deduce the upper and lower faces that are parallel to the highly conducting quasi-twodimensional planes by visual inspection.…”

Section: Methodsmentioning

confidence: 99%

Robust superconducting state in the low-quasiparticle-density organic metalsβ″−(BEDT−TTF)4[(
Bangura
¹
,
Coldea
²
,
Singleton
³

et al. 2005
Phys. Rev. B

View full text Add to dashboard Cite

We report magnetotransport measurements on the quasi-two-dimensional charge-transfer salts ␤Љ-͑BEDT-TTF͒ 4 ͓͑H 3 O͒M͑C 2 O 4 ͒ 3 ͔Y, with Y =C 6 H 5 NO 2 and C 6 H 5 CN using magnetic fields of up to 45 T and temperatures down to 0.5 K. A surprisingly robust superconducting state with an in-plane upper critical field B c2ʈ Ϸ 33 T, comparable to the highest critical field of any BEDT-TTF superconductor, and critical temperature T c Ϸ 7 K is observed when M = Ga and Y =C 6 H 5 NO 2 . The presence of magnetic M ions reduces the in-plane upper critical field to Ϸ18 T for M = Cr and Y =C 6 H 5 NO 2 and M = Fe and Y =C 6 H 5 CN. Prominent Shubnikov-de Haas oscillations are observed at low temperatures and high magnetic fields, showing that the superconducting salts possess Fermi surfaces with one or two small quasi-two-dimensional pockets, their total area comprising Շ6% of the room-temperature Brillouin zone; the quasiparticle effective masses were found to be enhanced when the ion M was magnetic ͑Fe or Cr͒. The low effective masses and quasiparticle densities, and the systematic variation of the properties of the ␤Љ-͑BEDT-TTF͒ 4 ͓͑H 3 O͒M͑C 2 O 4 ͒ 3 ͔Y salts with unit-cell volume points to the possibility of a superconducting groundstate with a charge-fluctuation-mediated superconductivity mechanism such as that proposed by Merino and McKenzie ͓Phys. Rev. Lett. 87, 237002 ͑2001͔͒, rather than the spin-fluctuation mechanism appropriate for the -͑BEDT-TTF͒ 2 X salts.

show abstract

Section: Methodsmentioning

confidence: 99%

Robust superconducting state in the low-quasiparticle-density organic metalsβ″−(BEDT−TTF)4[(
Bangura
¹
,
Coldea
²
,
Singleton
³

et al. 2005
Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…13,14 Moreover, a rich variety of superconductors is available among the ␤Љ-type ET salts. [17][18][19][20][21] Throughout the experiment, for several ␤Љ-type ET salts, we can investigate what dictates the site charges around the phase boundary as well as in the insulating phase without a theoretical simulation.…”

Section: Introductionmentioning

confidence: 99%

“…The electrical resistivity for group II shows a weak increase with decreasing temperature below ϳ100 K, with the sol= PhNO 2 salt exhibiting an I-SC transition at ambient pressure. 21,22,24 On the other hand, the SC transition is not observed for the sol= pyridine and CH 2 Cl 2 salts at either ambient or hydrostatic pressure. 21,24 Since Shubnikov-de Haas oscillations are observed for the sol = pyridine salt, the non-SC salts are inherently metal.…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneous site charges at the boundary between the insulating, superconducting, and metallic phases ofβ″-type bis-ethylenedithio-tetrathiafulvalene molecular charge-transfer salts

Yamamoto

Kato

et al. 2008

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

We have examined time-averaged charges of the molecular donors around the phase boundary between the insulating, superconducting, and metal phases for ␤Љ-type ET ͓ET= bis-ethelenedithio-tetrathiafulvalene͔ salts with one ͑two͒ hole͑s͒ per two ͑three͒ molecules by using vibrational spectroscopy. Around the phase boundary, the site charges are neither those expected for a well-developed charge-ordered ͑CO͒ state nor a homogeneous distribution. The molecular charges exhibit an inhomogeneous distribution just above the insulatorsuperconductor transition temperature. We have analyzed the distribution of the site charges from the viewpoint of the alternation of intersite Coulomb interactions along the stacking direction. The closeness in the energy of several CO patterns mostly contributes to the inhomogeneous distribution, whereas a large difference ͑no difference͒ in the energy levels contributes to the CO ͑homogeneous͒ state. Our observations indicate that the instability due to the closeness in the energy of several distributions correlates with the insulatorsuperconductor transition in nondimerized or weakly dimerized molecular conductors.

show abstract

“…In a previous NMR experiment the character of the charge-ordered state could not be investigated because of limitations in the spectral resolution at low magnetic fields. In this Rapid Communication we explore the static properties of the charge-ordered state by analyzing the highly resolved NMR spectra taken at 15 T and precisely quantify the site-charge modulation that appears near the SC transition.A single crystal of β -Ga salt was prepared with an electrochemical oxidation process [19]. The typical sample dimension was 2 × 1 × 0.2 mm 3 .…”

mentioning

confidence: 99%

“…A single crystal of β -Ga salt was prepared with an electrochemical oxidation process [19]. The typical sample dimension was 2 × 1 × 0.2 mm 3 .…”

mentioning

confidence: 99%

C13NMR study of the charge-ordered state near the superconducting transition in the organic superconductorβ′′−(BEDT-T

et al. 2014

View full text Add to dashboard Cite

The charge-ordered state in a quasi-two-dimensional organic superconductor β -(BEDT-TTF) 4 [(H 3 O)Ga(C 2 O 4 ) 3 ]·C 6 H 5 NO 2 has been investigated using 13 C NMR spectroscopy in a high magnetic field. Enhanced resolution of the high-field spectrum allows us to estimate the site charges in the low-temperature charge-ordered state below 8.5 K. The observed strong increase in the charge imbalance suggests that superconductivity appears on the electronic state with a strong charge modulation. From the NMR intensity ratio of signals from the charge-rich and charge-poor sites, we discuss a possible charge pattern with threefold modulation, which could be stabilized by the effects of electron-electron correlations. Unconventional superconductivity is frequently observed near the boundary of other ordered phases. In high-T c pnictides and heavy fermion superconductors, superconductivity appears next to an antiferromagnetic phase, and its mechanism is related to the critical fluctuations of the second-order phase transition. By analogy with antiferromagnetism near superconductivity, the charge-ordering (CO) transition near the superconducting (SC) phase would also be related to the SC pairing mechanisms. In fact, it has been suggested theoretically that the charge fluctuations can contribute to form Cooper pairs both in the context of cuprates [1] and layered molecular crystals [2]. As in most of materials the SC and CO transitions appear at very different temperatures, particular attention should be paid to rare examples where these transitions (and related energy scales) are close [3], to reveal experimentally the complex relationship, perhaps not only competition, between the CO and SC phases.Electronic charge localization is caused by a strong electron-electron interaction in half-filled or quarter-filled systems. The effects of on-site and off-site Coulomb interactions have been intensively investigated both from theoretical and experimental points of view [4][5][6]. In low-dimensional electronic systems, such as NbSe 3 [7] and organic conductor (TMTTF) 2 X (tetramethyltetrathiafulvalene) salts [8], the charge-density-wave (CDW) state with fractional charge localization is driven by Fermi surface instability. Although these systems show superconductivity under pressure, the CDW state of NbSe 3 is completely suppressed when superconductivity sets in [9], and in (TMTTF) 2 X a magnetic phase appears between the SC and CDW phases. Charge instability is also observed in quasi-two-dimensional organic conductors (BEDT-TTF) 2 X [bis(ethylenedithio)-tetrathiafulvalene] salts. In some BEDT-TTF salts, superconductivity appears directly after the suppression of the CO transition by applying chemical or mechanical pressure [10][11][12]. However, the CO transition temperature is much higher than the SC transition temperature T c [13,14], and the two phenomena thus appear * yihara@phys.sci.hokudai.ac.jp unrelated. In the BEDT-TTF salt with β -type molecular packing, β -(BEDT-TTF) 4 [(H 3 O)Ga(C 2 O 4 ) 3 ]·C 6 H 5 NO 2 (β -Ga)...

show abstract

Effect of Included Guest Molecules on the Normal State Conductivity and Superconductivity of β‘ ‘-(ET)₄[(H₃O)Ga(C₂O₄)₃]·G (G = Pyridine, Nitrobenzene)

Cited by 90 publications

References 5 publications

Robust superconducting state in the low-quasiparticle-density organic metalsβ″−(BEDT−TTF)4[(
Bangura
¹
,
Coldea
²
,
Singleton
³

et al. 2005
Phys. Rev. B

Robust superconducting state in the low-quasiparticle-density organic metalsβ″−(BEDT−TTF)4[(
Bangura
¹
,
Coldea
²
,
Singleton
³

et al. 2005
Phys. Rev. B

Inhomogeneous site charges at the boundary between the insulating, superconducting, and metallic phases ofβ″-type bis-ethylenedithio-tetrathiafulvalene molecular charge-transfer salts

C13NMR study of the charge-ordered state near the superconducting transition in the organic superconductorβ′′−(BEDT-T

Contact Info

Product

Resources

About

Effect of Included Guest Molecules on the Normal State Conductivity and Superconductivity of β‘ ‘-(ET)4[(H3O)Ga(C2O4)3]·G (G = Pyridine, Nitrobenzene)

Cited by 90 publications

References 5 publications

Robust superconducting state in the low-quasiparticle-density organic metalsβ″−(BEDT−TTF)4[(Bangura1, Coldea2, Singleton3 et al. 2005Phys. Rev. B

Robust superconducting state in the low-quasiparticle-density organic metalsβ″−(BEDT−TTF)4[(Bangura1, Coldea2, Singleton3 et al. 2005Phys. Rev. B

Inhomogeneous site charges at the boundary between the insulating, superconducting, and metallic phases ofβ″-type bis-ethylenedithio-tetrathiafulvalene molecular charge-transfer salts

C13NMR study of the charge-ordered state near the superconducting transition in the organic superconductorβ′′−(BEDT-T

Contact Info

Product

Resources

About

Effect of Included Guest Molecules on the Normal State Conductivity and Superconductivity of β‘ ‘-(ET)₄[(H₃O)Ga(C₂O₄)₃]·G (G = Pyridine, Nitrobenzene)

Robust superconducting state in the low-quasiparticle-density organic metalsβ″−(BEDT−TTF)4[(
Bangura
¹
,
Coldea
²
,
Singleton
³

et al. 2005
Phys. Rev. B

Robust superconducting state in the low-quasiparticle-density organic metalsβ″−(BEDT−TTF)4[(
Bangura
¹
,
Coldea
²
,
Singleton
³

et al. 2005
Phys. Rev. B