A detailed investigation of the out-of-plane electrical properties of charge-ordered alpha-(BEDT-TTF)2I3 provides clear evidence for ferroelectricity. Similar to multiferroic alpha-(BEDT-TTF)2Cu[N(CN)2]Cl, the polar order in this material is ascribed to the occurrence of bond- and site-centered charge order. Dielectric response typical for relaxor ferroelectricity is found deep in the charge-ordered state. We suggest an explanation in terms of the existence of polar and nonpolar stacks of the organic molecules in this material, preventing long-range ferroelectricity. The results are discussed in relation to the formation or absence of electronic polar order in related charge-transfer salts.
@article{arxiv.1407.0339,
title = {Ferroelectric properties of charge-ordered alpha-(BEDT-TTF)2I3},
author = {P. Lunkenheimer and B. Hartmann and M. Lang and J. Müller and D. Schweitzer and S. Krohns and A. Loidl},
journal= {arXiv preprint arXiv:1407.0339},
year = {2015}
}
Comments
8 pages, 4 figures. Revised version as accepted for publication in Phys. Rev. B