EPR detection of presumable magnetoelectric interactions in the liquid-crystalline state of an iron mesogen

The behavior of the iron-containing mesogenic molecules in the magnetic field was studied by EPR in ferroelectric-like smectic phases. The investigation of the angular dependence of the EPR spectra allows one to define the unusual orientation of the iron molecules in the external magnetic field. Different factors influencing the way of the molecules' orientation in the magnetic field were considered and evaluated. It is shown that the unusual orientation is, most probably, caused by the action of the internal electric field (existing in the mesophases) on magnetic properties via the magnetoelectric effect. It is also found that the paramagnetic susceptibility of the iron complex in mesophases is increased, and that it has an anomaly in the same temperature range as the static dielectric permittivity does. It is supposed, that this anomaly is also associated with the creation of an additional magnetization by the internal electric field. (C) 2003 Elsevier B.V. All rights reserved.