Europhys. Lett.
Volume 75, Number 2, July 2006
Page(s) 301 - 307
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 14 June 2006
Europhys. Lett., 75 (2), pp. 301-307 (2006)
DOI: 10.1209/epl/i2006-10096-6

Self-organization of charge under pressure in the organic conductor $\rm {(TMTSF)_2ReO_4}$

C. Colin1, P. Auban-Senzier1, C. R. Pasquier1 and K. Bechgaard2

1  Laboratoire de Physique des Solides, UMR8502 - Bat. 510, Centre Universitaire F-91405 Orsay Cédex, France
2  Department of Chemistry, H.C. Oersted Institute - Univeristetsparken 5 DK-2100, Copenhagen, Denmark

received 29 March 2006; accepted 24 May 2006
published online 14 June 2006

$\rm {(TMTSF)_2ReO_4}$ presents a phase coexistence between two anion orderings defined by their wave vectors q2=(1/2,1/2,1/2) and q3=(0,1/2,1/2) in a wide range of pressure (8-11$\un{kbar}$) and temperature. From the determination of the anisotropy of the conductivity and the superconducting transitions in this regime we were able to extract the texture which results from a self-organization of the orientations of the $\rm {ReO_4^{-}}$ anions in the sample. At the lowest pressures, the metallic parts, related to the q3 order, form droplets elongated along the a-axis embedded in the semiconducting matrix associated with the q2 order. Above 10$\un{kbar}$, filaments along the a-axis extend from one end of the sample to the other nearly up to the end of the coexistence regime. A mapping of the system into an anisotropic Ising lattice is satisfactory to analyze the data.

74.70.Kn - Organic superconductors.
72.60.+g - Mixed conductivity and conductivity transitions.
72.80.Le - Polymers; organic compounds (including organic semiconductors).

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