Title: Probing Acoustic Dynamics in Ferroelectrics by Microwave Imaging

Keji Lai
University of Texas
Wednesday, April 18, 2018
4:00 pm
NS2 1201
Conventional dielectric spectroscopy probes the dynamics of ions, dipoles, atoms, and electrons in bulk materials. Using a microwave impedance microscope, we show that the giga-Hertz dynamic response to external stimuli can now be spatially resolved down to the mesoscopic length scale. In hexagonal manganites, the dissipation of electrical energy on certain ferroelectric domain walls (DWs) is substantially enhanced at microwave frequencies. First-principles and model calculations indicate that the effect is associated with a localized vibrational mode. In addition to the DW oscillation, the local electromechanical energy transduction in ferroelectric domains can also be visualized by the impedance microscopy. The interference patterns vividly demonstrate the spatial variation of surface-acoustic-wave generation efficiency. Our work opens up a new frontier to explore various acousto-electronic phenomena in complex materials and novel devices. 
Jing Xia