Modern transmission electron microscopy and its application to multiferroic materials

Recent progress of a variety of modern transmission electron microscopy(TEM) techniques and their applications to multiferroic materials are briefly reviewed. It is emphasized that numerous significant structural issues in multiferroic material science could be well addressed by means of TEM-based techniques. For instance, atomic-resolution scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) are invaluable for determining the atomic structure, valence states and electronic structure of the controllable interface in multiferroic heterostructures. High-quality high-resolution TEM and STEM images with spatial resolution better than 1Å ensure the direct observation of local dipoles and mapping of the polarization field. The new generation TEM facilities combined with in-situ cooling/heating and electric/magnetic field holders allow us to capture the dynamic characteristics of the atomic structure and ferroelectric/magnetic domains and to understand the interaction between different order parameters, which will provide valuable insight into the physical origin of the coupling mechanism in multiferroics.