Imaging Ultrafast and Ultrasmall: Understanding and Manipulating Phase Transitions in Correlated Oxides Using Coherent X-Ray Diffraction

非技术描述：现代半导体器件在包括信息技术、能源、健康和教育在内的各个领域取得了重要进展。为了克服现有微电子性能的瓶颈，实现高能效的高速运行，复合氧化物已被确定为半导体的可能替代品。本项目探索利用光学激光在超快时间尺度上操纵复杂氧化镍的磁性和电子特性的新方法。研究活动包括在纳米长度尺度和飞秒时间尺度上合成和高级表征复合氧化物。对纳米尺度和超快现象的基本理解预计将对未来几代计算设备的发展产生重大影响。教育活动包括向女性和少数族裔本科生介绍美国国家实验室的机会，并与加州大学戴维斯分校数学工程科学成就（MESA）学校项目合作，使高中生参与科学、技术、工程和数学。该项目将为研究生和本科生提供材料科学、物理和电气工程交叉领域的培训。毕业生很可能在信息技术领域找到未来的工作。技术细节：本研究项目的目标是阐明在相关氧化物（包括稀土镍酸盐，如镍酸钕和镍酸钐）的超小长度尺度和超快时间尺度上定制材料性能的基本限制和机制。该项目主要利用同步加速器和基于相干x射线的自由电子激光技术，研究稀土镍酸盐薄膜的光诱导金属绝缘体相变。具体目标包括：(i)破译与超快行为相关的基本长度尺度和时间尺度，（ii）理解纳米尺度形貌在光诱导相变中的影响，以及（iii）研究飞秒时间尺度上电子、磁性和结构自由度的耦合。在这个项目中发现的材料行为的超快/超小前沿的最终极限的科学知识将使基于光-物质相互作用的未来几代计算设备的发展成为可能。教育活动包括培训本科生和研究生使用最先进的沉积和表征工具，包括美国国家实验室的同步辐射和基于自由电子激光的表征技术。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: Modern-day semiconductor devices have led to important advances in diverse areas including information technology, energy, health, and education. To overcome the current plateau in performance of the existing microelectronics and enable energy-efficient high-speed operation, complex oxides have been identified as a possible alternative to semiconductors. This project explores the novel approach of utilizing optical lasers to manipulate magnetic and electronic properties of complex nickel oxides at ultrafast timescales. Research activities involve synthesis and advanced characterization of complex oxides at nanometer lengthscales and femtosecond timescales. The fundamental understanding of nanoscale and ultrafast phenomenon is expected to significantly impact the development of future generations of computing devices. Education activities includes introducing women and minority undergraduate students to opportunities at U.S. National Laboratories and collaborating with University of California Davis Mathematics Engineering Science Achievement (MESA) Schools Program to engage high school students in science, technology, engineering, and mathematics. This project will provide graduate and undergraduate students training in interdisciplinary fields at the intersection of materials science, physics, and electrical engineering. Graduates are likely to find future employment in the information technology sector. TECHNICAL DETAILS: The goal of this research project is to elucidate fundamental limits and mechanisms to tailor material properties at ultrasmall lengthscales and ultrafast timescales in correlated oxides including rare-earth nickelates such as neodymium nickelate and samarium nickelate. The project focuses on optically induced metal-insulator phase transitions in rare earth nickelate thin films by utilizing synchrotron and free electron laser based coherent X-ray techniques. Specific objectives include: (i) deciphering fundamental lengthscales and timescales associated with ultrafast behavior, (ii) understanding the influence of nanoscale morphology in optically induced phase transitions, and (iii) investigating the coupling of electronic, magnetic and structural degrees of freedom at femtosecond timescales. The scientific knowledge at the ultimate limits of the ultrafast/ultrasmall frontier in materials behavior discovered in this project will enable development of future generations of computing devices based on light-matter interactions. Education activities include the training of undergraduate and graduate students in state-of-the art deposition and characterization tools, including synchrotron radiation and free electron laser-based characterization techniques at U.S. National Laboratories.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.