Order Parameters and Phase Diagram of Multiferroic RMn2O5
Abstract
The generic magnetic phase diagram of multiferroic RMn2O5 (with R=Y, Ho, Tb, Er, Tm), which allows different sequences of ordered magnetic structures for different R's and different control parameters, is described using order parameters which explicitly incorporate the magnetic symmetry. A phenomenological magneto-electric coupling is used to explain why some of these magnetic phases are also ferroelectric. Several new experiments, which can test this theory, are proposed.
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