Landau model for the phase diagrams of the orthorhombic rare-earth manganites RMnO3

The present work aims to describe, within a single phenomenological approach, the specific sequence of phase transitions observed in the rare-earth manganites RMnO3 at zero magnetic field. It is shown that a single integrated description of the temperature versus composition phase diagrams of these compounds and related solid solutions can be obtained within the scope of Landau theory by adopting the so called type-II description of the modulated phases.