Tuning the magnetic dimensionality by charge ordering in the molecular TMTTF salts

TL;DR

This paper explores how charge ordering influences magnetic states in TMTTF salts, revealing that ferroelectric charge order enhances 2D antiferromagnetism while different spin-Peierls states emerge in 1D regimes, with key parameters identified through calculations.

Contribution

The study combines theoretical analysis and first-principles calculations to elucidate the role of charge order in tuning magnetic dimensionality in TMTTF salts.

Findings

Charge order enhances two-dimensional antiferromagnetic correlations.

Different spin-Peierls states are stabilized in one-dimensional regimes.

Interchain transfer integrals and charge order amplitude control the phase diagram.

Abstract

We theoretically investigate the interplay between charge ordering and magnetic states in quasi-one-dimensional molecular conductors TMTTF$_2X$, motivated by the observation of a complex variation of competing and/or coexisting phases. We show that the ferroelectric-type charge order increases two-dimensional antiferromagnetic spin correlation, whereas in the one-dimensional regime two different spin-Peierls states are stabilized. By using first-principles band calculations for the estimation for the transfer integrals and comparing our results with the experiments, we identify the controlling parameters in the experimental phase diagram to be not only the interchain transfer integrals but also the amplitude of the charge order.