Pressure-induced charge-transfer and structural transition in hexagonal multiferroic HoMnO3
The structural properties of the hexagonal multiferroic h-HoMnO3 under high pressure have been explored using synchrotron x-ray diffraction and x-ray absorption spectroscopy in diamond anvil cells. The structure was found to undergo a pressure-induced phase transition at ∼24 GPa to a rhombohedrally distorted superstructure, which is isostructural to the oxygen-loaded h-RMnO3+δ (R=Y,Dy,Ho,Er; δ≈0.2