Local Structure of Multiferroic TbMn2O5: Evidence for an Anomalous Terbium Oxygen Distribution

摘要

The temperature dependent local structure of TbMn2O5 was determined by x-rayabsorption spectroscopy. An anomalous Tb-O distribution is found. At hightemperature it is broad but resolves into two distinct peaks belowapproximately 180 K. The distributions sharpen below the Tb magnetic orderingtemperature (approximately 10 K). The distortions in the Tb-O distribution,away from the Pbam structure, are consistent with rotations of the MnOxpolyhedra about the c-axis and suggest that Tb-O bond polarization may play asignificant role in the observed ferroelectric properties of this system.