Static and dynamic properties of hexagonal multiferroic RMnO3 compounds

The magnetic and electric static and dynamic properties of hexagonal multiferroic RMnO3 are studied based on the transverse Ising and Heisenberg models using a Green's function technique. The influence of the magnetoelectric coupling and the exchange interaction constants is discussed. The coexistence of ferroelectricity and magnetism leads to interplay between the electric and magnetic properties which was found as an anomaly, as a kink in the temperature dependence of different static and dynamic properties in the vicinity of the magnetic phase transition temperature T-N. The spin excitations show a novel softening around T-N due to the magnetoelectric coupling. The magnetic-field-induced polarization is investigated. The obtained results are in qualitative agreement with the experimental data. (C) 2007 American Institute of Physics.