Self-organization of charge under pressure in the organic conductor (TMTSF)2ReO4

TL;DR

This study investigates how charge self-organizes under pressure in the organic conductor (TMTSF)2ReO4, revealing phase coexistence, anisotropic conductivity, and filament formation through experimental and modeling approaches.

Contribution

It provides new insights into charge organization and phase coexistence in (TMTSF)2ReO4 under pressure, using anisotropic conductivity measurements and Ising lattice modeling.

Findings

Phase coexistence between two anion orderings over a pressure range.

Formation of elongated metallic droplets and filaments along the a-axis.

Mapping to an anisotropic Ising lattice explains the observed textures.

Abstract

(TMTSF)2ReO4 presents a phase coexistence between two anion orderings defined by their wave vectors q_2=(1/2,1/2,1/2) and q_3=(0,1/2,1/2) in a wide range of pressure (8-11kbar) 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 ReO4 anions in the sample. At the lowest pressures, the metallic parts, related to the q_3 order, form droplets elongated along the a-axis embedded in the semiconducting matrix associated with the q_2 order. Above 10kbar, 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. satisfactory to analyze the data.