Engineering Interface Magnetism via Defect Control in Complex Oxide Heterostructures

*复合氧化物材料已被证明是发现新的有用物理现象的非凡平台。将这些材料组装成人工异质结构，为新科学的发现和铁电随机存取存储器、燃料电池和自旋电子学等领域的应用提供了大量的进一步机会。然而，为了充分利用这些材料，必须解决一些严重的开放问题，特别是关于界面应变和缺陷的问题。这个项目的目标正是为了实现这一点，使用钴氧化物作为模型系统来理解应变状态、氧空位形成和有序化以及界面磁性/电子输运之间的相互作用。具体的机会包括使用对氧缺陷的应变控制来精确设计界面的磁性和电学性质，以及合成无缺陷材料的可能性，以探索最近理论预测的新物理。这项研究的影响将远远超出其开展的直接学科，因为它与新兴技术相关，为学生提供了特殊的教育机会，并纳入了代表性不足的群体。还将通过开发明尼阿波利斯公立学校系统物质属性模块的互动演示来向公众宣传，影响到数百名8年级学生。*非技术摘要*复合氧化物由多个金属元素的原子与氧结合而成，是一组在物理和化学性质上显示出非凡多样性的材料，产生了一些最重要的物理学发现。最近认识到的将这些材料结合到人造结构中的能力，其中多个氧化物被层叠在一起，具有原子尺度的精度，这为在广泛的各种应用中充分利用它们的性质提供了一种手段。其中包括零启动时间存储器、清洁燃烧燃料电池和低功耗高速电子产品。然而，关键的悬而未决的问题阻碍了这一领域的进展，特别是与缺失的氧原子有关的有害缺陷的形成。在这个项目中，使用了一组特定的复杂氧化物材料来了解控制这些缺陷的形成和排列的因素，它们对性能的影响，以及我们可以控制它们的方法。最终目标是能够精确地控制氧化物界面上的电子和磁性行为，以便在各种新设备中充分利用其独特的特性。这项研究将产生广泛的影响，因为它与新兴技术相关，为学生提供了特殊的教育机会，并纳入了代表性不足的群体。还将通过开发明尼阿波利斯公立学校系统物质属性模块的互动演示来向公众宣传，影响到数百名8年级学生。

****Technical Abstract****Complex oxide materials have proven to be an extraordinary platform for discovery of new and useful physical phenomena. Assembling these materials into artificial heterostructures provides a plethora of further opportunities, both for discovery of new science, and for applications in areas such as ferroelectric RAM, fuel cells, and spintronics. However, in order to fully exploit these materials some serious open issues must be resolved, particularly with respect to interfacial strain and defects. The goal of this project is to achieve exactly this, using cobalt oxides as model systems to understand the interplay between strain state, oxygen vacancy formation and ordering, and interface magnetism/electronic transport. Specific opportunities include the use of strain-control over oxygen defects to precisely engineer interfacial magnetic and electronic properties, and the possibility of synthesizing defect-free materials to probe new physics recently predicted by theory. The research will have impact well beyond the immediate disciplines in which it is performed, due to its relevance to emerging technologies, the exceptional educational opportunities provided to students, and inclusion of under-represented groups. Outreach to the public will also be achieved via development of an interactive presentation for the Properties of Matter module in the Minneapolis Public School System, impacting hundreds of 8th grade students. ****Non-Technical Abstract****Complex oxides, formed by bonding atoms of multiple metallic elements with oxygen, are a set of materials that display extraordinary diversity in physical and chemical properties, yielding some of the most important discoveries in physics. The recently recognized ability to incorporate these materials into artificial structures where multiple oxides are laminated together, with atomic-scale precision, provides a means to fully exploit their properties in a wide variety of applications. These include zero boot-up time memory, clean-burning fuel cells, and low power consumption high-speed electronics. However, critical unsolved issues hinder progress in this area, particularly the formation of unwanted defects associated with missing oxygen atoms. In this project a specific set of complex oxide materials are being used to understand what factors control the formation and arrangement of these defects, the influence they have on properties, and the means by which we can control them. The ultimate goal is to be able to precisely control electronic and magnetic behavior at oxide interfaces in order to fully exploit their unique properties in a wide variety of new devices. The research will have broad impact due to its relevance to emerging technologies, the exceptional educational opportunities provided to students, and inclusion of under-represented groups. Outreach to the public will also be achieved via development of an interactive presentation for the Properties of Matter module in the Minneapolis Public School System, impacting hundreds of 8th grade students.