Novel Oxide-Based Magneto-Electric Tunnel Junctions

本研究的目的是制备和研究具有有源多铁性或铁电势垒的磁性隧道结--称为磁电隧道结。传统的磁性隧道结代表了一类利用电子自旋来实现其性能的器件。提出的磁电隧道结是基于理论预测，这些预测将不对称性确定为获得多功能器件的基本标准。这些器件有望同时表现出磁阻和电阻效应，再加上微妙的电子传输效应。计划了一个全面的研究计划，解决与以下组件相关的问题：样品制造、结构表征、纳米级磁电性能和器件表征。该计划的基本重点将是研究具有超薄铁电和多铁质势垒的磁电隧道结及其复合材料的磁电输运特性。这项研究的智力价值在于利用对电子性质的基本见解以及创新的制造和表征方法来研究新型异质结构，这些方法有可能实现一类新的多态电阻器件。应使用最先进的脉冲激光沉积技术和单元控制来制造原型器件。器件特性应在纳米级和全球级进行研究。纳米尺度的表征将涉及使用导电原子力显微镜的双层结构的电流-电压特性。用压电响应力显微镜研究超薄膜的局域铁电开关特性。将在橡树岭国家实验室的纳米材料科学中心进行先进的扫描探头表征，研究纳米级铁电和隧道特性。更广泛的影响包括多学科努力，这将对科学知识、教育推广和基础设施做出重大贡献。预计该项目的科学成果将包括一种新型隧道连接结构的制造进展，以及对其材料和物理特性的基本了解。设备研究将为实现多功能设备提供坚实的基础，如果成功，将产生非凡的影响，并为更多的应用打开大门。该计划将为研究生和本科生提供支持，包括未被充分代表的少数族裔，并为他们广泛的跨学科培训做出贡献。项目人员将与当地学校合作，促进高中生参与研究。

The objective of this research is to fabricate and study magnetic tunnel junctions with an active multiferroic or ferroelectric barrier - termed magneto-electric tunnel junctions. Traditional magnetic tunnel junctions represent a class of device that utilizes the electronic spin for its performance. The proposed magneto-electric tunnel junctions are based on theoretical predictions that have identified asymmetry as a fundamental criterion for obtaining multi-functional devices. These devices are expected to exhibit simultaneous magneto-resistance and electro-resistance effects, coupled with subtle electronic transport effects. A comprehensive research program is planned which addresses issues related to the following components: sample fabrication, structural characterization, nanoscale magneto-electric properties, and device characterization. The basic focus of the proposed program will be on the investigation of magneto-electric transport properties of magneto-electric tunnel junctions with ultra-thin ferroelectric and multiferroic barriers and their composites. The intellectual merit of the research lies in the investigation of novel heterostructures utilizing fundamental insight into electronic properties coupled with innovative fabrication and characterization methods that have the potential for realizing a new class of multiple-state resistance devices. State-of-the-art pulsed laser deposition techniques shall be used with unit-cell control to fabricate prototype devices. Device characteristics shall be investigated both at the nanoscale and global level. Nanoscale characterization would involve current-voltage characteristics of bilayer structures using conducting atomic force microscopy. Local ferroelectric switching properties of ultra-thin films shall be studied using piezoresponse force microscopy. Advanced scanning probe characterization investigating nanoscale ferroelectricity and tunneling properties shall be performed at the Center for Nanoscale Material Sciences at the Oak Ridge National Laboratory. The Broader Impacts includes a multidisciplinary effort that will make significant contributions to scientific knowledge, education outreach and infrastructure. The scientific outcomes of the project are expected to include both advances in the fabrication of a new class of tunnel junction structures and fundamental understanding of their materials and physical characteristics. Device studies will provide a firm foundation for realizing multifunctional devices and, if successful, would have an extraordinary impact and open the door for a plethora of applications. The program will provide support for graduate and undergraduate students, including underrepresented minorities, and contribute to their broad interdisciplinary training. Project personnel will collaborate with local schools to facilitate participation by high school students in research.