Hexagonal Manganites—(RMnO3): Class (I) Multiferroics with Strong Coupling of Magnetism and Ferroelectricity
Figure 25
Schematic order of the Mn spins (left) and Ho magnetic moments (right) in different magnetic phases of HoMnO3. (a) , in zero magnetic field, (b) , in zero magnetic field, (c) , (suspected high-field symmetry, the relative alignment of the FM sublattices of Ho 2a and 4b can also be antiferromagnetic resulting in a ferrimagnetic state, possibly at lower magnetic fields), and (d) , for in zero magnetic field. Note that (d) allows for a magnetic order of the moments on 4b sites, but it was not observed experimentally. The Ho ions and their magnetic moments in two neighboring unit cells are shown.
