Conduction anisotropy and Hall effect in the organic conductor (TMTTF)2AsF6: evidence for Luttinger liquid and charge ordering

TL;DR

This study investigates the anisotropic resistivity and Hall effect in (TMTTF)2AsF6, revealing high-temperature Luttinger liquid behavior and charge ordering phenomena through detailed transport measurements.

Contribution

It provides experimental evidence for Luttinger liquid features and charge ordering in (TMTTF)2AsF6, advancing understanding of quasi-one-dimensional organic conductors.

Findings

High-temperature resistivity anisotropy shows metallic behavior only along the a-axis.

Hall coefficient is positive, enhanced, and nearly constant above 220 K.

Charge ordering transition occurs around 100 K, significantly altering Hall effect behavior.

Abstract

We present the high-temperature (70 K < T < 300 K) resistivity anisotropy and Hall effect measurements of the quasi-one-dimensional (1D) organic conductor (TMTTF)2AsF6. The temperature variations of the resistivity are pronouncedly different for the three different directions, with metallic-like at high temperatures for the a-axis only. Above 220 K the Hall coefficient R_H is constant, positive and strongly enhanced over the expected value; and the corresponding carrier concentration is almost 100 times lower than calculated for one hole/unit cell. Our results give evidence for the existence of a high-temperature regime above 200 K where the 1D Luttinger liquid features appear in the transport properties. Our measurements also give strong evidence of charge ordering in (TMTTF)2AsF6. At the charge-ordering transition T_{CO} \approx 100 K, R_H(T) abruptly changes its behavior, switches sign and rapidly increases with further temperature decrease.