1208.0633 (S. Iguchi et al.)

Relaxor ferroelectricity induced by electron correlations in a molecular
dimer Mott insulator    [PDF]

S. Iguchi, S. Sasaki, N. Yoneyama, H. Taniguchi, T. Nishizaki, T. Sasaki

We have investigated the dielectric response in an antiferromagnetic dimer-Mott insulator beta'-(BEDT-TTF)2ICl2 with square lattice, compared to a spin liquid candidate kappa-(BEDT-TTF)2Cu2(CN)3. Temperature dependence of the dielectric constant shows a peak structure obeying Curie-Weiss law with strong frequency dependence. We found an anisotropic ferroelectricity by pyrocurrent measurements, which suggests the charge disproportionation in a dimer. The ferroelectric actual charge freezing temperature is related to the antiferromagnetic interaction, which is expected to the charge-spin coupled degrees of freedom in the system.

View original: http://arxiv.org/abs/1208.0633