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Chiba, R.; Hiraki, K.; Takahashi, Toshihiro; Yamamoto, Hiroshi; Nakamura, Toshikazu

doi:10.1103/physrevlett.93.216405

Cited by 58 publications

(42 citation statements)

References 23 publications

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“…The linewidth shows a broadening as the temperature approaches T CO [15]. Chiba analyzed this behavior, and reported the following results [88]. Above T CO , fluctuation of CO arises in space (the fractional charge is distributed from +0.3 to +0.7) and in time (extremely slow on the time scale of 13 C-NMR).…”

Section: Metallic Phase Of X = Rbzn(scn) 4 Tlzn(scn) 4 Cu 2 Cn[n(mentioning

confidence: 99%

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

Yakushi

2012

Crystals

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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

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Section: Metallic Phase Of X = Rbzn(scn) 4 Tlzn(scn) 4 Cu 2 Cn[n(mentioning

confidence: 99%

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

Yakushi

2012

Crystals

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“…To prevent the Pake doublet effect, we enriched one side of the central C=C bond in BEDT-TTF molecules with 13 C nuclei [ Fig. 1(b)] by using the cross-coupling method.…”

Section: Methodsmentioning

confidence: 99%

“…The slow dynamics below ∼10 kHz contribute to the T 2 process. 12,13 At low temperatures, the ethylene motion shown in Fig. 3(a) is probably frozen.…”

Section: B Ethylene Dynamics Of Bedt-ttf Moleculementioning

confidence: 99%

“…1 Figure 2(a) shows the temperature dependence of the linewidths in the 13 C-NMR spectrum of κ-(BEDT-TTF) 2 Cu(NCS) 2 . The linewidths increase with decreasing temperature from room temperature to a maximum at around 90 K; the linewidths then decrease with decreasing temperature to about 50 K, where they begin increasing again due to magnetic impurities.…”

Section: A Linewidth and T 2 Anomalymentioning

confidence: 99%

“…One is that the ethylene motion causes a direct fluctuation in the local field via the dipole interaction; the other is that conduction electron causes an indirect fluctuation in the local field. To determine whether the mechanism is direct or indirect, we substituted 13 C nuclei for one side of the central C=C bond in the BEDT-TTF molecule and 2 D nuclei for the 1 H nuclei of the ethylene groups. While Kawamoto et al 17 observed remarkable isotope effects in κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Br, no significant isotope effect was reported including the lattice constants and the electromagnetic properties in the paramagnetic phase of κ-(BEDT-TTF) 2 Cu(NCS) 2 .…”

Section: Coupling Mechanism Of T 2 Processmentioning

confidence: 99%

See 2 more Smart Citations

Low-frequency dynamics ofκ-(BEDT-TTF)2Cu(NCS)2
Kuwata
¹
,
Itaya
²
,
Kawamoto
³

2011
Phys. Rev. B
17
4
25
0
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κ-(BEDT-TTF) 2 Cu(NCS) 2 [BEDT-TTF: bis-(ethylenedithio)-tetrathiafulvalene] behaves as a semiconductor at high temperatures, whereas it behaves as a Fermi liquid just above the superconducting transition temperature. To reveal the cause of this behavior, we experimented on κ-(BEDT-TTF) 2 Cu(NCS) 2 , in which one side of the central C=C in the BEDT-TTF molecules is substituted with 13 C nuclei. We perfomed 13 C-nuclear magnetic resonance (NMR) spectroscopy on this salt and measured the temperature dependence of its spectral linewidths and its spin-spin relaxation time T 2 . We found anomalies in its linewidths and T 2 , which we connected to the ethylene motion within the salt. Compared with the 13 C-NMR measurements of κ-(BEDT-TTF-d8) 2 Cu(NCS) 2 , we obtained the experimental evidence of the connection between the ethylene motion and the conduction electrons. Considering this connection, we examined the semiconductive behavior of κ-(BEDT-TTF) 2 Cu(NCS) 2 at high temperatures. The contribution of ethylene motion to the electronic state is thought to be a common feature of BEDT-TTF salts.

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Possibility of Dielectric Material: Magnetic Resonance Study of Oxo‐Bridged Dinuclear Ruthenium Mixed‐Valence Complex

et al. 2018

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Solid‐state broad line 1H‐NMR (nuclear magnetic resonance) and ESR (electron spin resonance) were performed for an oxo‐bridged dinuclear ruthenium [RuORu]5+ (Ru3.5+ORu3.5+) mixed‐valence complex. The 1H‐NMR spin‐lattice relaxation rate T1−1 was significantly enhanced, to below 100 K with a peak at approximately 33 K. The T1−1 peak temperature was frequency‐independent, indicating that this anomaly is a possible phase transition. Below approximately 40 K, an abrupt decrease of 1H‐NMR spin‐spin relaxation time T2 provides evidence of the appearance of inequivalent 1H‐sites (sudden decrease in symmetry). ESR spectra suddenly disappeared above 35 K. The electronic properties and possible charge ordering (Ru3+ORu4+) states in this mixed‐valence compound are discussed from a microscopic point of view.

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Extremely Slow Charge Fluctuations in the Metallic State of the Two-Dimensional Molecular Conductorθ−(BEDT−T

Cited by 58 publications

References 23 publications

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

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

Low-frequency dynamics ofκ-(BEDT-TTF)2Cu(NCS)2
Kuwata
¹
,
Itaya
²
,
Kawamoto
³

2011
Phys. Rev. B
17
4
25
0
View full text Add to dashboard Cite

Possibility of Dielectric Material: Magnetic Resonance Study of Oxo‐Bridged Dinuclear Ruthenium Mixed‐Valence Complex

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Extremely Slow Charge Fluctuations in the Metallic State of the Two-Dimensional Molecular Conductorθ−(BEDT−T

Cited by 58 publications

References 23 publications

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

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

Low-frequency dynamics ofκ-(BEDT-TTF)2Cu(NCS)2Kuwata1, Itaya2, Kawamoto3 2011Phys. Rev. B174250View full textAdd to dashboardCite

Possibility of Dielectric Material: Magnetic Resonance Study of Oxo‐Bridged Dinuclear Ruthenium Mixed‐Valence Complex

Contact Info

Product

Resources

About

Low-frequency dynamics ofκ-(BEDT-TTF)2Cu(NCS)2
Kuwata
¹
,
Itaya
²
,
Kawamoto
³

2011
Phys. Rev. B
17
4
25
0
View full text Add to dashboard Cite