Nanoscale Investigation of Microwave Dynamics in Novel Ferroelectric Microstructures

非技术摘要：对于具有永久电偶极子的材料，在微波区与振荡电磁场的相互作用导致能量耗散。在铁电材料中，由偶极损耗引起的有效交流电导率可能与由移动电子引起的直流电导率有很大的不同。研究小组使用专门的显微镜，旨在研究铁电样品对微波激励的局部响应，自发极化的快速切换，以及基于结构动力学的器件结构的可行性。铁电微结构中纳米尺度微波动力学的基础知识可能直接影响其在纳米技术中的应用，并导致新的器件结构。得克萨斯大学奥斯汀分校建立了一个综合研究和教育计划，以培养不同水平的学生参与基础材料研究并掌握先进的显微技术。技术摘要：具有复杂磁畴结构的块状铁电材料由于具有较强的介电色散，通常与微波应用不兼容。然而，如果人们能够通过寻址单独的磁区壁和其他新的极性结构来利用局部的介电损耗，情况可能会不同，这是不平凡的，因为执行纳米级阻抗谱的难度很大。利用频率可调的微波阻抗显微镜，该研究小组计划研究许多深刻的科学问题，如磁区壁、涡旋和极天子对微波激励的局部响应，以及铁电薄膜在强驱动场下的千兆赫兹极化开关。新型极组态的集体微波动力学是涌现现象的生动例证。研究结果对铁电微结构在通信系统中的应用也具有重要意义。先进材料和技术的研究活动与通过实验室体验、周六研讨会和夏令营向当地高中生推广相结合。积极参与前沿研究将影响他们在物理或其他STEM领域的职业道路。这项DMR拨款支持在强交流驱动磁场下了解铁电薄膜微结构的研究，资金来自数学和物理科学总监材料研究部的凝聚态物质物理(CMP)计划。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.