Y-O hybridization in the ferroelectric transition of YMnO3

The electron density distribution of paraelectric and ferroelectric YMnO3 are investigated by analyzing high temperature synchrotron radiation powder diffraction data using the maximum entropy method (MEM) and MEM-based pattern fitting combined with the Rietveld method. The results show that chemical bonding by orbital hybridization is established between the Y and in-plane O ions along the polar c-axis below the ferroelectric transition temperature. We suggest that the hybridization observed in the ferroelectric phase is the driving force for ferroelectricity in YMnO3. (C) 2009 American Institute of Physics. [doi:10.1063/1.3233943]