Nanoscale Investigation of Microwave Dynamics in Novel Ferroelectric Microstructures

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Nontechnical Abstract: For materials with permanent electric dipoles, the interaction with an oscillating electromagnetic field leads to energy dissipation in the microwave regime. In ferroelectric materials, the effective alternating-current conductivity due to dipolar loss can be very different from the direct-current conductivity due to mobile electrons. Using a specialized microscope, the research team aims to study the local response of ferroelectric samples to microwave excitations, the fast switching of spontaneous polarizations, and the feasibility of device structures based on structural dynamics. The fundamental knowledge on the nanoscale microwave dynamics in ferroelectric microstructures may directly influence their applications in nanotechnology and lead to novel device configurations. An integrated research and education program at University of Texas at Austin is established such that students at different levels are trained to participate in fundamental material research and master advanced microscopy techniques.Technical Abstract: Bulk ferroelectrics with complex domain structures are usually not compatible with microwave applications because of the strong dielectric dispersion. The situation, however, could be different if one can take advantage of the localized dielectric loss by addressing individual domain walls and other novel polar structures, which is nontrivial because of the difficulty to perform nanoscale impedance spectroscopy. Using a microwave impedance microscope with tunable frequencies, the research team plans to study many profound scientific questions such as the local response of domain walls, vortices, and polar skyrmions to microwave excitations and the giga-Hertz polarization switching of ferroelectric thin films under strong driving fields. The collective microwave dynamics of novel polar configurations is a vivid demonstration of emergent phenomena. The results are also critical for the applications of ferroelectric microstructures in communication systems. The research activities on advanced materials and technologies are integrated with outreach to local high school students through lab experience, Saturday workshop, and summer camps. The active involvement in frontier research will influence their career path towards physics or other STEM fields.This DMR grant supports research to understand microstructures within ferroelectric thin films under strong AC driving fields with funding from the Condensed Matter Physics (CMP) Program in the Division of Materials Research of the Mathematical and Physical Sciences Directorate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.