Dielectric response of the charge-induced correlated state in the quasi-one-dimensional conductor(TMTTF)2PF6

Abstract

Dear Editors,We would like to submit our manuscript entitled "Dielectric response of charge induced correlated state in quasi-one-dimensional conductor (TMTTF) 2 PF 6 " for publication in Phys. Rev. We previously submitted it to Phys. Rev. Lett. (code number LH7335).The delay for resubmission has been caused by difficulties in communication between coauthors, one at Moscow, another visiting Japan during several weeks. We would like, however, the original received date to be retained. The manuscript has been amended according to the referee comments as described below :Referee A 1) We modified our description of the extended Mott-Hubbard model for half-filled bands (bottom of page 2) taking into account both the on-site interaction (U) and the near-neighbor interaction (V).2) The 2k F lattice fluctuations coupled to the lattice are observed at much lower temperature (below 60 K) than the large increase of the dielectric permittivity. We have rewritten the beginning of the discussion part, page 6, to make this point more clear. Referee B1) These organic conductors are very fragile and cracks may reflect significant strain when the cooling rate is too fast and/or the sample holding too tight. We used all the care possible for avoiding cracks in our crystals and thus measuring bulk properties.2) There is no evidence in (TMTTF) 2 PF 6 of a structural phase transition affecting the main Bragg reflections. The tentative explanation of our data is the occurrence of a superstructure (4k F ) transition. Such a transition could be very likely detected from NMR experiments.Yours sincerely, P. MONCEAU C e n t r e d e R e c h e r c h e s s u r l e s T rè s B a s s e s T e m pé r a t u r e s laboratoire associéà l'Université Joseph Fourier

Relaxor ferroelectricity induced by electron correlations in a molecular dimer Mott insulator

“…This discovery will enable a deeper understanding of organic Mott insulators beyond the successful dimer lattice model and the discovery of new functionality. The origin of this ferroelectricity is different from the recently discovered hydrogen-bonded organic ferroelectrics 12 and the Peierls instability-induced inversion symmetry breaking in one-dimensional systems 13 .…”

Slowing down of the relaxational dynamics at the ferroelectric phase transition in one-dimensional (TMTTF)2AsF6

“…Without the local maximum at T c , our τ(T) may be described just as in [7], namely by thermally activated behavior with a decrease of the effective energy barrier below T c . Vice versa, it can be argued that in (TMTTF) 2 PF 6 , while the tendency exists, the maximum of τ(T) at T c is not observed because the transition is much more smeared out compared to (TMTTF) 2 AsF 6 .…”

“…This transition bears the characteristics of ferroelectric (FE) order in dielectric spectroscopy, as deduced from the Curie-Weiss like divergence of the dielectric constant [5,6,7,8]. As optical measurements [9] gave no evidence for a FE soft-mode expected for a second-order displacive transition, Brazovskii et al proposed [10] that a soft mode in TMTTF probably is accessible at low frequencies, consistent with a non negligible lowfrequency dispersion [6,7].…”

“…As optical measurements [9] gave no evidence for a FE soft-mode expected for a second-order displacive transition, Brazovskii et al proposed [10] that a soft mode in TMTTF probably is accessible at low frequencies, consistent with a non negligible lowfrequency dispersion [6,7]. A theoretical proposal [5,10] relates the FE transition to the change of the average phase in the charge channel of the Luttingerliquid ground state, which is balanced by the spatial shift of the anions, leading to a displacive transition of second order.…”

Charge, spin, and lattice effects in the spin-Peierls ground state of MEM(TCNQ)2

“…In the (TMTTF) 2 PF 6 compound for instance, the transition takes place at T SP ≈ 18 K at ambient pressure for the salt with hydrogenated TMTTF molecule [10][11][12] and at 13 K in the deuterated one [13]. These quasi-1D materials, however, display a slightly dimerized structure leading to a Mott insulating gap below T ρ ≈ 230K [14], followed by a charge ordered superstructure (CO) at T CO ≈ 65K [15,16](T CO ≈ 84K in deuterated [17,18]) whose proximity with the SP transition has prevented the full characterization of its order parameter. Indeed, inhomogeneous dielectric [18] and elastic [19] behaviors were observed in the vicinity of the SP transition for the hydrogenated and deuterated PF 6 salts.…”