Influence of Charge Order on the Ground States of TMTTF Molecular Salts

TL;DR

This study investigates how charge order influences the ground states of TMTTF molecular salts under pressure, revealing interactions between charge order, Spin-Peierls, and antiferromagnetic phases through NMR spectroscopy.

Contribution

It provides new insights into the interplay between charge order and magnetic ground states in TMTTF salts, extending the phase diagram with pressure effects.

Findings

Charge order and Spin-Peierls order parameters are repulsive.

Antiferromagnetic state is stabilized by large charge order.

Pressure modifies the phase boundaries in TMTTF salts.

Abstract

(TMTTF)2AsF6 and (TMTTF)2SbF6 are both known to undergo a charge ordering phase transition, though their ground states are different. The ground state of the first is Spin-Peierls, and the second is an antiferromagnet. We study the effect of pressure on the ground states and the charge-ordering using 13C NMR spectroscopy. The experiments demonstrate that the the CO and SP order parameters are repulsive, and consequently the AF state is stabilized when the CO order parameter is large, as it is for (TMTTF)2SbF6. An extension of the well-known temperature/pressure phase diagram is proposed.