Correlation-driven electronic multiferroicity in TMTTF2-X organic crystals

Using a combination of density functional theory and dynamical mean field theory we show that electric polarization and magnetism are strongly intertwined in TMTTF2-X (X=PF6,AsF6, and SbF6) organic crystals. 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. The value of the electronic polarization is enhanced by the onset of antiferromagnetism showing a sizable magnetoelectric effect which predicts the multiferroic behavior of TMTTF2-X compounds.