Functional Transport Properties of Multiferroics

*技术摘要*铁电材料中的电荷传导，通常被称为漏电，一直被认为是一个严重的问题，降低了它们的功能。然而，最近已经报道了具有非零d电子的多铁体铁电畴和铁电壁中显著的电子输运性质。这些新颖的特性包括铁电磁区的显著导电、偏振调制整流和可切换的光伏效应。该提案设想的目标是在受控环境中使用标准输运测量和扫描探针显微镜(SPM)来表征包括极性磁体在内的高质量半导体多铁性单晶中单个磁区和壁的电荷传导和光伏效应的潜在机制。我们将利用透射电子显微镜、同步加速器X射线和中子散射来研究晶体结构和磁结构与电荷输运性质的关系。这一结果将对开发基于纳米级功能传输特性的潜在技术具有重要意义，例如阻性铁电存储器、传感器和新型能量采集设备。基础研究与研究生、本科生和高中生教育的整合将是关键部分。高中生将通过新泽西州自由科学中心组织的科学伙伴计划参与其中。来自拟议项目的新研究成果将是关于最新材料物理学的研究生课程的宝贵部分。*非技术摘要*磁性和铁电性是当前技术的必要基础，而磁性和铁电性共存的多铁性材料已被广泛研究，具有重大的技术和基础科学意义。然而，多铁体中前所未有的功能电荷输运性质直到最近才被揭示。该提案设想的目标包括表征多铁体中功能电荷传输特性的机制，以及开发基于纳米级功能传输特性的潜在技术，如阻性铁电存储器、传感器和新型能量采集设备。该提案的核心是广泛的合作，因此将利用多种技术和技能。拟议的研究将进一步加强研究在各级教育中的作用。例如，高中生将通过由新泽西州泽西市自由科学中心组织的科学伙伴计划参与拟议的研究，过去11年来，PI一直参与该计划，来自提议项目的新研究成果将成为关于最新材料物理的研究生课程的宝贵部分。

****Technical Abstract****Charge conduction in ferroelectrics, more often called leakage, has been considered a serious problem that depreciates their functionality. However, remarkable electronic transport properties have been recently reported in ferroelectric domains and walls in multiferroics with non-zero d electrons. These novel properties include significant conduction in ferroelectric domain walls, polarization-modulated rectification, and switchable photovoltaic effects. The objective envisioned in the proposal is to characterize the underlying mechanisms of charge conduction and photovoltaic effects of individual domains and walls in high-quality single crystals of semiconducting multiferroics, including polar magnets, using standard transport measurements and Scanning Probe Microscopy (SPM) in controlled environments. Crystallographic and magnetic structural correlation with charge transport properties will be investigated using transmission electron microscopy (TEM), and synchrotron x-ray and neutron scattering. The results will be important in order to exploit potential technologies based on nanoscale functional transport properties, such as resistive ferroelectric memories, sensors, and novel energy-harvest devices. Integration of fundamental research and education of graduate, undergraduate and high-school students will be a critical part. High school students will be involved through the Partners in Science Program, organized by the liberty Science Center, New Jersey. New research results from the proposed projects will be a valuable part of a graduate course on up-to-date materials physics.****Non-Technical Abstract****Magnetism and ferroelectricity are imperative bases for current technology and multiferroic materials, where magnetism and ferroelectricity coexist, have been extensively investigated for great technological and fundamental scientific importance. However, the unprecedented functional charge transport properties in multiferroics have been only recently revealed. The objectives envisioned in the proposal include to characterize the mechanism of the functional charge transport properties in multiferroics, and to exploit potential technologies based on nanoscale functional transport properties, such as resistive ferroelectric memories, sensors, and novel energy-harvest devices. The centerpiece of the proposal is a wide spectrum of collaboration, so a multiplicity of techniques and skills will be utilized. The proposed study will further strengthen the role of research in all levels of education. For example, high school students will be involved in the proposed research through the Partners in Science program, organized by the Liberty Science Center, Jersey City, New Jersey, which the PI has been continuously involved in for the last 11 years, and new research results from the proposed projects will be a valuable part of a graduate course on up-to-date materials physics.