Probing Domain Wall Dynamics in Ferroic Materials by Impedance Microscopy

非技术摘要：铁电体或铁磁体中的磁畴壁是分隔具有不同极化或磁化强度的磁畴的边界。这些窄界面的运动对于这些材料在电子和光学器件中的应用是至关重要的。由于各种技术挑战，从实验上研究单个磁区壁的高频动力学并不是一件容易的事。研究小组使用一种专门的显微镜，旨在研究这些纳米尺寸界面的电学性质，以及探索在微波频率下工作的域壁设备。德克萨斯大学奥斯汀分校建立了一个综合的研究和教育项目，以培养不同水平的学生探索基础材料物理并掌握先进的显微技术。技术摘要：为了了解铁性材料的开关动力学，集体磁场壁运动得到了广泛的研究。然而，由于很难在很宽的频率范围内进行纳米级阻抗谱的研究，人们对铁磁畴壁对振荡电场的动态响应知之甚少，这对于它们在功能器件中的应用至关重要。利用一种新型的宽带阻抗显微镜，研究小组计划解决许多深刻的科学问题，如铁性磁区壁上的介电损耗和导电性、温度和磁场对磁区壁上动力学的影响，以及制作磁区壁波导原型的可行性。了解微波区多铁磁区壁介电色散和局域电导对于它们在通信系统中的应用是至关重要的。纳米介电光谱的新方法处于现代凝聚态物理的前沿。关于先进材料和技术的研究活动还与通过星期六讲习班和夏令营向当地高中生和教师进行的外联活动相结合。

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.