Epitaxial growth of multiferroic Y Mn O₃ on GaN

n this work, we report on the epitaxialgrowth of multiferroic Y Mn O₃ on GaN. Both materials are hexagonal with a nominal lattice mismatch of 4%, yet x-ray diffraction reveals an unexpected 30° rotation between the unit cells of Y Mn O₃ and GaN that results in a much larger lattice mismatch (10%) compared to the unrotated case. Estimates based on first principles calculations show that the bonding energy gained from the rotated atomic arrangement compensates for the increase in strain energy due to the larger lattice mismatch. Understanding the energy competition between chemical bonding energy and strain energy provides insight into the heteroepitaxialgrowth mechanisms of complex oxide-semiconductor systems