Oral Presentation 24th Australian Conference on Microscopy and Microanalysis 2016

Towards quantitative mapping of electric fields in ferroelectrics (#71)

Daniel J Taplin 1 , Matthew Weyland 2 3 , Naoya Shibata 4 , Scott D Findlay 1
  1. School of Physics and Astronomy, Monash University, Clayton, Victoria, Australia
  2. Monash Centre for Electron Microscopy, Monash University, Clayton, Victoria, Australia
  3. Department of Materials Science and Engineering, Monash University, Clayton, Victoria, Australia
  4. Institute of Engineering Innovation, University of Tokyo, Tokyo, Japan

Determining the nanoscale electromagnetic field distribution within materials is important for both understanding and developing functional properties of materials and devices.  One technique for imaging nanoscale field structure using a scanning transmission electron microscope (STEM) is differential phase contrast (DPC) imaging, whereby a position-sensitive detector in the diffraction plane converts lateral deflections of the electron beam induced by the electromagnetic fields within the sample into visible contrast.  We discuss the use of STEM DPC for low-to-medium resolution mapping of polarized domain structures in ferroelectric or polar materials such as BaTiO3.1  Using simulations, we show how factors such as specimen mistilt, detector non-uniformity, screening, dynamical electron scattering and noise all impact on the extent to which electric fields can be reliably and quantitatively mapped.  The conditions under which the internal electric fields of ferroelectric or polar materials can best be quantitatively measured are discussed.  The materials ZnO, BaTiO3, and LiNbO3 are used as case studies for low, medium and high saturation polarization materials.  As we will show, both segmented detectors and pixel detectors show much promise for identifying fields via DPC with a STEM.

This research was supported under the Discovery Projects funding scheme of the Australian Research Council (Project nos. DP110101570 and DP140102538).

  1. N. Shibata, S. D. Findlay, Y. Kohno, H. Sawada, Y. Kondo and Y. Ikuhara, Nature Physics 8, 611-615 (2012).