Probing Domain Wall Dynamics in Ferroic Materials by Impedance Microscopy

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Non-Technical Abstract: Domain walls in ferroelectrics or ferromagnets are the boundaries separating domains with different polarizations or magnetizations. The motion of these narrow interfaces is of fundamental importance for the application of these materials in electrical and optical devices. Because of various technical challenges, it is not trivial to experimentally investigate the high-frequency dynamics of individual domain walls. Using a specialized microscope, the research team aims to study the electrical properties of these nanometer-sized interfaces, as well as to explore domain wall devices that function at microwave frequencies. An integrated research and education program at University of Texas at Austin is established such that students at different levels are trained to explore fundamental material physics and master advanced microscopy techniques.Technical Abstract: The collective domain wall motion has been extensively studied to understand the switching dynamics of ferroic materials. Due to the difficulty to perform nanoscale impedance spectroscopy over a broad frequency range, however, little is known about the dynamic response of ferroic domain walls to oscillating electric fields, which is crucial for their application in functional devices. Using a novel broadband impedance microscope, the research team plans to address many profound scientific questions such as the dielectric loss and conduction at ferroic domain walls, the influence of temperature and magnetic fields on wall dynamics, and the feasibility of prototyping domain wall waveguides. The understanding of the dielectric dispersion and local conduction of multiferroic domain walls in the microwave regime is critical for their application in communication systems. The new approach of nanoscale dielectric spectroscopy is at the cutting edge of modern condensed matter physics. The research activities on advanced materials and technologies are also integrated with outreach to local high school students and teachers through Saturday workshop and summer camps.