Correlation-driven electronic multiferroicity in (TMTTF)$_2$-$X$ organic crystals

TL;DR

This study demonstrates that in (TMTTF)$_2$-$X$ organic crystals, electronic correlations induce a multiferroic state where electric polarization and magnetism are strongly coupled, revealing potential for magnetoelectric applications.

Contribution

The paper shows that short-range Coulomb interactions lead to multiferroicity in (TMTTF)$_2$-$X$ crystals, combining charge order, ferroelectricity, and magnetism in a novel way.

Findings

Electronic correlations induce charge order and ferroelectricity.

Antiferromagnetism enhances electronic polarization.

The compounds exhibit sizable magnetoelectric coupling.

Abstract

Using a combination of density functional theory and dynamical mean field theory we show that electric polarization and magnetism are strongly intertwined in (TMTTF)$_2$-$X$ (X$=$PF$_6$, As$F_6$, and SbF$_6$) organic crystals and they originate from short-range Coulomb interactions. Electronic correlations induce a charge-ordered state which, combined with the molecular dimerization, gives rise to a finite electronic polarization and to a ferroelectric state. We predict that the value of the electronic polarization is enhanced by the onset of antiferromagnetism showing a sizable magnetoelectric leading to a multiferroic behavior of (TMTTF)$_2$-$X$ compounds.