"Origin of the large polarization in multiferroic YMnO3 thin films revealed by soft and hard x-ray diffraction"
H. Wadati, J. Okamoto, M. Garganourakis, V. Scagnoli, U. Staub, Y. Yamasaki, H. Nakao, Y. Murakami, M. Mochizuki, M. Nakamura, M. Kawasaki, and Y. Tokura
Physical Review Letters 108, 047203-1-5, 2012