Magnetism and Charge ordering in TMTTF$_2$-PF$_6$ organic crystals

TL;DR

This study combines theoretical methods to uncover a multiferroic phase in TMTTF$_2$-PF$_6$ organic crystals, characterized by charge and spin order, structural dimerization, and ferroelectricity.

Contribution

It demonstrates the emergence of a magnetically driven dimerized charge ordered state and its coexistence with ferroelectricity in TMTTF$_2$-PF$_6$.

Findings

Identification of a dimerized charge ordered state

Coexistence of charge order with ferroelectricity

Magnetically driven dimerization as a multiferroic mechanism

Abstract

Using a combination of Density Functional Theory, mean-field analysis and exact diagonalization calculations we reveal the emergence of a dimerized charge ordered state in TMTTF$_2$-PF$_6$ organic crystal. The interplay between charge and spin order leads to a rich phase diagram. Coexistence of charge ordering with a structural dimerization results in a ferroelectric phase, which has been observed experimentally. The tendency to the dimerization is magnetically driven revealing TMTTF$_2$-PF$_6$ as a multiferroic material.