EAGER: Probing High-Frequency Dynamics of Individual Domain Walls in Ferroelectrics

非技术摘要：铁电体，磁铁的电对应物，通常分为许多域。分隔不同畴的边界，称为畴壁，可以在铁电基器件中振动和吸收微波功率。迄今为止，由于各种技术挑战，对单个铁电畴壁的高频运动知之甚少。使用一种特殊的显微镜，研究小组的目标是通过它们吸收电磁能量的能力来可视化畴壁。这项研究所获得的知识对于这些材料未来的电子应用至关重要。德克萨斯大学奥斯汀分校建立了一个综合性的研究和教育项目，培养研究生和本科生探索基础材料物理和掌握先进的显微技术。技术摘要：铁电畴壁宽度为几个纳米，通常表现出不同的属性域，这可能会主导整个系统的电动力学响应。例如，人们认为，在高频介电色散中起关键作用的是壁，而不是畴。然而，由于商业阻抗分析仪缺乏灵敏度，很难将磁畴和磁畴壁的贡献与传统的体测量分开。利用一种新的宽带阻抗显微镜与纳米级分辨率，本研究旨在局部探测铁电畴壁在不同温度下的高频响应。中性和带电畴壁在适当的和不适当的铁电体正在调查中。这项工作是重要的，因为它是第一个实验研究铁电动力学下降到纳米长度尺度，它有助于解决有争议的微观图片集体畴壁振动。了解铁电体在微波区的本征介电色散对于它们在通信系统中的应用也是至关重要的。EAGER项目中提出的纳米介电谱的新方法可能会为现代凝聚态物理研究带来变革性的结果。

Non-technical Abstract:Ferroelectrics, the electric counterpart of magnets, are usually self-divided into many domains. The boundaries separating different domains, known as the domain walls, may vibrate and absorb microwave power in ferroelectric-based devices. To date, very little is known about the high-frequency motion of individual ferroelectric domain walls due to various technical challenges. Using a special microscope, the research team aims to visualize the domain walls by their ability to absorb the electromagnetic energy. The knowledge obtained by this research is crucial for future electronic applications of these materials. An integrated research and education program at University of Texas at Austin is established such that graduate and undergraduate students are trained to explore fundamental material physics and master advanced microscopy techniques.Technical Abstract: Ferroelectric domain walls with widths of several nanometers usually exhibit properties distinct from that of the domains, which may dominate the electrodynamic responses of the entire system. For instance, it is believed that the walls, rather than the domains, play the key role in the high-frequency dielectric dispersion. Due to the lack of sensitivity in commercial impedance analyzers, however, it has been difficult to separate the contributions of domains and domain walls from conventional bulk measurements. Using a novel broadband impedance microscopy with nanoscale resolutions, this research aims to locally probe the high-frequency response of ferroelectric domain walls at variable temperatures. Both neutral and charged domain walls in proper and improper ferroelectrics are under investigation. The work is significant because it is the very first experimental study on ferroelectric dynamics down to the nanometer length scale and it helps to resolve the controversial microscopic picture of the collective domain wall vibrations. The understanding of the intrinsic dielectric dispersion of ferroelectrics in the microwave regime is also critical for their applications in communication systems. The new approach of nanoscale dielectric spectroscopy proposed in this EAGER project may lead to transformative results for modern condensed matter physics research.