J. Phys. IV France 12 (2002) Pr9-139
DOI: 10.1051/jp4:20020380

Influence of charge order on the ground state of TMTTF conductors

F. Zamborszky^{1, 2}, W. Yu², W. Raas², S.E. Brown², B. Alavi², C.A. Merlic³, A. Baur³, S. Lefebvre² and P. Wzietek<sup>4

1</sup>  Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547, U.S.A.
²  Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.A.
³  Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095-1569, U.S.A.
⁴  Laboratoire de Physique des Solides, URA 2 du CNRS, Université Paris-Sud, bâtiment 510, 91405 Orsay, France

Abstract
Properties of the charge-ordered (CO) phase for the representative salt (TMTTF) ₂AsF ₆ are determined using ¹³C and ⁷⁵As nuclei as probes. The charge disproportionation ratio is found to be at least 3:1 at temperatures below the transition temperature T . At lower temperatures, the material undergoes a second transition to a singlet ground state. Investigations of the relative stability of the two orders under applied pressure reveal that the two orders compete. The phase diagram consists of a region of coexistence and a tetracritical point.

© EDP Sciences 2002