B. Alavi

Charge ordering in the TMTTF family of molecular conductors

Using one- and two-dimensional NMR spectroscopy applied to 13C spin-labeled (TMTTF)2AsF6 and (TMTTF)2PF6, we demonstrate the existence of an intermediate charge-ordered phase in the TMTTF family of charge-transfer salts. At ambient temperature, the spectra are characteristic of nuclei in equivalent molecules. Below a continuous charge-ordering transition temperature T(co), there is evidence for two inequivalent molecules with unequal electron densities. The absence of an associated magnetic anomaly indicates only the charge degrees of freedom are involved and the lack of evidence for a structural anomaly suggests that charge-lattice coupling is too weak to drive the transition.

Competition and coexistence of bond and charge orders in (TMTTF)2AsF6

(TMTTF) 2 AsF 6 undergoes two phase transitions upon cooling from 300 K. At T C O = 103 K a charge ordering (CO) occurs, and at T S P (B = 9 T) = 11 K the material undergoes a spin-Peierls transition. Within the intermediate, CO phase, the charge disproportionation ratio is found to be at least 3:1 from 1 3 C NMR T - 1 1 measurements on spin-labeled samples. Above T S P up to about 3T S P T - 1 1 is independent of temperature, indicative of low-dimensional magnetic correlations. With the application of about 0.15 GPa pressure, T S P increases substantially, while T C O is rapidly suppressed, demonstrating that the two orders are competing. The experiments are compared to results obtained from calculations on the one-dimensional extended Peierls-Hubbard model.

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

The temperature/pressure phase diagram for

The transition from a pseudogapped metal to an insulator : photoemission and optics of (TMTSF)2ReO4

{(\mathrm{TMTTF})}_{2}{\mathrm{SbF}}_{6}

NMR as a probe of incommensurate spin density waves in organic metals

is determined using

NMR evidence for very slow carrier density fluctuations in the organic metal (TMTSF)2ClO4

^{13}\mathrm{C}

NMR in the pseudogap- and charge-density-wave states of (TaSe4)2I

NMR spectroscopy. At ambient pressure, a transition to a charge-ordered (CO) state occurs at

The spin-density-wave gap in (TMTSF)2ClO4

{T}_{\mathrm{CO}}=156\phantom{\rule{0.3em}{0ex}}\mathrm{K}

Inhomogeneous carrier density and the role of disorder in the normal state of (TMTSF)2PF6

, and antiferromagnetic (AF) order is observed below

Evidence that the SDW phase transition in (TMTSF)2PF6 is first order

{T}_{N}=8\phantom{\rule{0.3em}{0ex}}\mathrm{K}