Electron-lattice coupling and broken symmetries of the molecular salt(TMTTF)2SbF6

The temperature/pressure phase diagram for ${(\mathrm{TMTTF})}_{2}{\mathrm{SbF}}_{6}$ is determined using $^{13}\mathrm{C}$ NMR spectroscopy. At ambient pressure, a transition to a charge-ordered (CO) state occurs at ${T}_{\mathrm{CO}}=156\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, and antiferromagnetic (AF) order is observed below ${T}_{N}=8\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Both are suppressed with pressure: when $Pg0.5\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, there is no evidence for CO, and the low-temperature $^{13}\mathrm{C}$ NMR spectrum is consistent with a singlet [spin-Peierls (SP)] ground state. At a given pressure, the temperature dependence of the CO order parameter is not monotonic, and provides an opportunity to identify what processes could be controlling the CO amplitude. $^{19}\mathrm{F}$ NMR spectroscopy provides empirical evidence that electron-counterion coupling is crucial to stabilizing the CO and AF phases.

[1]  W. Yu,et al.  Influence of charge order on the ground states of TMTTF molecular salts , 2003, cond-mat/0312387.

[2]  R. T. Clay,et al.  Pattern of charge ordering in quasi-one-dimensional organic charge-transfer solids , 2003 .

[3]  Toshikazu Nakamura.  Possible Charge Ordering Patterns of the Paramagnetic Insulating States in (TMTTF)2X , 2003 .

[4]  M. Kuwabara,et al.  Coexistence of Charge Order and Spin-Peierls Lattice Distortion in One-Dimensional Organic Conductors , 2003, cond-mat/0301208.

[5]  P. Monceau,et al.  Charge ordering and ferroelectric states in organic quasi-one-dimensional conductors , 2002 .

[6]  S. Brazovskii,et al.  Theory of the ferroelectric Mott-Hubbard phase in organic conductors , 2002, cond-mat/0304483.

[7]  W. Yu,et al.  Competition and coexistence of bond and charge orders in (TMTTF)2AsF6 , 2002, cond-mat/0205026.

[8]  Jose RieraDidier Poilblanc.  Influence of the anion potential on the charge ordering in quasi-one-dimensional charge-transfer salts , 2001, cond-mat/0102531.

[9]  S. Brazovskii,et al.  Ferroelectric Mott-Hubbard phase of organic (TMTTF)2X conductors. , 2000, Physical review letters.

[10]  J. Riera,et al.  Coexistence of charge density waves, bond order waves and spin density waves in quasi-one dimensional charge transfer salts , 2000, cond-mat/0006460.

[11]  Brown,et al.  Charge ordering in the TMTTF family of molecular conductors , 2000, Physical review letters.

[12]  R. T. Clay,et al.  Bond-order and charge-density waves in the isotropic interacting two-dimensional quarter-filled band and the insulating state proximate to organic superconductivity , 2000, cond-mat/0003200.

[13]  D. Tantillo,et al.  Synthesis of Carbon-13 Labeled Tetramethyltetrathiafulvalene , 1999 .

[14]  R. T. Clay,et al.  Theory of Coexisting Charge and Spin-Density Waves in (TMTTF)2Br, (TMTSF)2PF6 and α-(BEDT-TTF)2MHg(SCN)4 , 1998, cond-mat/9807308.

[15]  H. Fukuyama,et al.  Antiferromagnetic phases of one-dimensional quarter-filled organic conductors , 1997, cond-mat/9704038.

[16]  S. Ravy,et al.  X-ray evidence of charge density wave modulations in the magnetic phases of (TMTSF)2PF6 and (TMTTF)2Br , 1997 .

[17]  S. Ravy,et al.  Structural Aspects of the Bechgaard Salts and Related Compounds , 1996 .

[18]  G. Bodenhausen,et al.  Principles of nuclear magnetic resonance in one and two dimensions , 1987 .

[19]  Parkin,et al.  Structureless transition and strong localization effects in bis-tetramethyltetrathiafulvalenium salts , 1985, Physical review. B, Condensed matter.

[20]  F. Wudl,et al.  Nuclear resonance and relaxation in ditetramethyltetraselenafulvalenium salts , 1982 .

[21]  H. Schulz,et al.  Organic conductors and superconductors , 1982 .