Reexamination of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mtext>C-NMR</mml:mtext><mml:mprescripts /><mml:none /><mml:mn>13</mml:mn></mml:mmultiscripts></mml:mrow></mml:math>in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mtext>TMTTF</mml:mtext></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow>

Hirose, Shinji; Kawamoto, Atsushi; Matsunaga, N.; Nomura, K.; Yamamoto, Kaoru; Yakushi, Kyuya

doi:10.1103/physrevb.81.205107

Cited by 20 publications

(30 citation statements)

References 24 publications

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“…5(a)], in which nodes are located at charge-poor molecules and antinodes at chargerich molecules. 12 The alternative arrangement, rich-poorrich-poor, in the CO state was confirmed by finding the second harmonic generation (SHG) in the absence of the lattice doubling. 23 In the case of the commensurate SDW, the antiferromagnetic fluctuation of the AsF 6 predicted the sinusoidal wave modulation.…”

Section: Magnetic Structure Of the Commensurate Antiferromagnetic mentioning

confidence: 73%

“…[9][10][11] The charge imbalance in the disproportionation state of (TMTTF) 2 AsF 6 , ρ = ρ rich − ρ poor , was estimated to be 0.16e by infrared spectroscopy. 12 We suggested a commensurate antiferromagnetic fluctuation in the CO paramagnetic state of (TMTTF) 2 AsF 6 from NMR study. We recently determined the magnetic structure of the antiferromagnetic phase (AF-I) of (TMTTF) 2 SbF 6 , 13 which is on the lower pressure side of (TMTTF) 2 AsF 6 .…”

Section: Introductionmentioning

confidence: 99%

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13C NMR study of commensurate antiferromagnetism in (TMTTF)2Br

2013

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Quasi-one-dimensional organic conductors (TMTCF) 2 X have various electric and magnetic properties. Although theoretical and experimental studies have suggested that (TMTTF) 2 Br has the properties of commensurate antiferromagnetism, details of the magnetic structure of this compound are unclear. Two types of antiferromagnetism are expected, one due to a localized electron and the other to the nesting of the Fermi surface. We therefore assessed the antiferromagnetic structure of (TMTTF) 2 Br using 13 C NMR. Site assignment of the observed antiferromagnetic spectrum confirmed that there were two magnetic molecular sites, with staggered moments and amplitude of 0.11μ B /molecule, as well as nonmagnetic molecular sites. A commensurate structure with antiferromagnetic ordering of (↑ • ↓ •) along a one-dimensional chain would be expected as the freezing of antiferromagnetic fluctuations in the charge-ordered phase of the (TMTTF) 2 AsF 6 salt. The presence of a nodal site is strongly suggestive of the nesting type antiferromagnetism. The fine structure of the antiferromagnetic spectrum suggests superlattice along the interchain direction. We could not observe line broadening due to the charge order above the antiferromagnetic transition.

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Section: Magnetic Structure Of the Commensurate Antiferromagnetic mentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

13C NMR study of commensurate antiferromagnetism in (TMTTF)2Br

2013

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“…As pointed out by several scholars [41,59,80,81], the antisymmetric ν 28 (b 1u ) stretching mode is probably the most sensitive local probe for charge disproportionation as it involves the outer C=C bonds of the fulvalene rings where most of the charge is accumulated as visualized in Figure 4. Although Hirose et al were able to observe this mode in their in-plane reflection measurements [41], a better and more direct approach consists in measuring in the perpendicular direction, i.e., E c where the electric field is mainly along the molecular axis and the background signal due to conduction electrons is lower.…”

Section: Conductivitymentioning

confidence: 93%

“…Below approximately 250 K a minimum in resistivity marks a localization of the charge due to on-site Coulomb interaction U ; the characteristic temperatures are listed in Table 1. Except (TMTTF) 2 ClO 4 , all Fabre salts develop a charge-ordered phase below T < T CO , as can be seen by a kink in ρ(T ) [ Figure 2b] [7,37,38], nuclear magnetic resonance (NMR) [10,11,15,39], electron spin resonance (ESR) [35,40], dielectric [18,20,22], and optical measurements [41][42][43][44][45]. While the magnetic properties at ambient temperature can be described as an antiferromagnetic chain according to the S = 1/2 Heisenberg model, the systems either exhibit a transition to an antiferromagnetic ground state or to a spin-Peierls state at low temperatures (Table 1) [46][47][48].…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Optical Investigations of Charge Order in Organic Chain Compounds (TMTTF)2X

et al. 2012

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Charge ordering in the (TMTTF) 2 X salts with centrosymmetric anions (X = PF − 6 , AsF − 6 , SbF − 6 ) leads to a ferroelectric state around 100 K. For the first time and in great completeness, the intra-and intermolecular vibrational modes of (TMTTF) 2 X have been investigated by infrared and Raman spectroscopy as a function of temperature and pressure for different polarizations. In this original paper, we explore the development and amount of charge disproportionation and the coupling of the electronic degrees of freedom to the counterions and the underlying lattice. The methyl groups undergo changes with temperature that are crucial for the anion cage formed by them. We find that the coupling of the TMTTF molecules to the hexafluorine anions changes upon cooling and especially at the charge-order transition, indicating a distortion of the anion. Additional features are identified that are caused by the anharmonic potential. The spin-Peierls transition entails additional modifications in the charge distribution. To complete the discussion, we also add the vibrational frequencies and eigenvectors based on ab-initio quantum-chemical calculations.

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“…12 It is not necessarily the case that the charge on the site is proportional to the spin on the site. 24 The wave function of the conduction electron with wave number vector k in ␣-͑BEDT-TTF͒ 2 I 3 is given as…”

Section: Spin Susceptibility At Ambient Pressurementioning

confidence: 99%

Local spin susceptibility in the zero-gap-semiconductor state ofα−(BEDT-TTF)2I3probed by
Hirose
¹
,
Kawamoto
²

2010
Phys. Rev. B
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␣-͑BEDT-TTF͒ 2 I 3 has a double column structure with three crystallographically independent molecules, A, B, and C, and becomes an insulator below 135 K due to a charge-ordering ͑CO͒ transition. The CO state is suppressed under pressure and shows weak temperature dependence of the electrical resistance. The decline of the carrier density is observed over 1.8 GPa, suggesting a zero-gap-semiconductor state under high pressure. The local susceptibility on each site provides important information about the electronic band structure. In our previous work, molecular site B became spin poor and molecular site C became spin rich in the metallic state, suggesting the disproportionation of the local spin density. Therefore, it is worthwhile to investigate the behavior of the electron properties of each molecular site. We accessed the 13 C-NMR in this salt at ambient pressure and at 2.1 GPa. The analysis of the local spin susceptibility suggests that the disproportionation of the spin susceptibility at 2.1 GPa is enhanced from that at ambient pressure, and the spin susceptibility vanishes at low temperature at 2.1 GPa. Moreover, from the temperature dependence of T 1 −1 , we obtain the relation of.

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Reexamination ofC-NMR13in(TMTTF)2

Cited by 20 publications

References 24 publications

13C NMR study of commensurate antiferromagnetism in (TMTTF)2Br

13C NMR study of commensurate antiferromagnetism in (TMTTF)2Br

Comprehensive Optical Investigations of Charge Order in Organic Chain Compounds (TMTTF)2X

Local spin susceptibility in the zero-gap-semiconductor state ofα−(BEDT-TTF)2I3probed by
Hirose
¹
,
Kawamoto
²

2010
Phys. Rev. B
Self Cite
12
2
15
0
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Reexamination ofC-NMR13in(TMTTF)2

Cited by 20 publications

References 24 publications

13C NMR study of commensurate antiferromagnetism in (TMTTF)2Br

13C NMR study of commensurate antiferromagnetism in (TMTTF)2Br

Comprehensive Optical Investigations of Charge Order in Organic Chain Compounds (TMTTF)2X

Local spin susceptibility in the zero-gap-semiconductor state ofα−(BEDT-TTF)2I3probed byHirose1, Kawamoto2 2010Phys. Rev. BSelf Cite122150View full textAdd to dashboardCite

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Local spin susceptibility in the zero-gap-semiconductor state ofα−(BEDT-TTF)2I3probed by
Hirose
¹
,
Kawamoto
²

2010
Phys. Rev. B
Self Cite
12
2
15
0
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