Naslov
Low temperature thermodynamical properties of the organic chain conductor (TMTTF)_2Br

Autori
Lasjaunias, Jean Claude ; Monceau, Pierre ; Starešinić, Damir ; Biljaković, Katica ; Fabre, Jean Michael

Izvornik
Journal de physique I (1155-4304) 7 (1997), 11; 1417-1429

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Low-energy excitations. Spin-density waves. Glass-transition. (TMTSF)2PF6. Charge. Heat. Phase. Commensurate. State.

Sažetak
We report on the first thermodynamical investigation of (TMTTF)_2Br in its antiferromagnetic ground state. There is a discontinuity in the lattice specific heat, C_p/T^3, at 1.9-2.0 K which seems to reflect the existence of the Spin Density Wave (SDW) sub-phase. This discontinuity is similar to those we have measured in other quasi one-dimensional organic salts of the Bechgaard family. Above 2.5 K there is another anomaly which we attribute either to a pure vibrational lattice origin or/and to an additional configurational entropy, a manifestation of the disordered SDW ground state coupled to the lattice. As for a broad variety of density wave compounds, the specific heat of (TMTTF)_2Br exhibits a contribution of low-energy excitations. They are at the origin of the time-dependent specific heat and complex energy-relaxation dynamics below 1 K. However, the corresponding time scale is much shorter than in the case of (TMTSF)_2PF_6, the Incommensurate SDW compound. We tentatively ascribe the difference in the kinetics of the energy relaxation of (TMTTF)_2Br and (TMTSF)_2PF_6 to the different degrees of commensurability of their ground states.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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