Materials World Network: Half Metallic Transport in Chemically Complex Systems

该奖项支持来自俄亥俄州立大学和德国德累斯顿莱布尼茨研究所（IFW）的国际合作研究团队，以实现和理解Heusler化合物和双钙钛矿的半金属性（即传导电子的100%自旋极化）。这两类复杂材料包含绝大多数具有高居里温度的半金属化合物，这些化合物有望在室温下实现高自旋极化输运。为了推进我们对这两个家族中自旋极化输运的基本理解和技术前景，这一合作伙伴关系汇集了俄亥俄州立大学在复杂材料的高质量外延膜沉积和自旋极化测量方面的互补专业知识，以及使用德国莱布尼茨研究所最先进的设备对这些材料进行单晶生长。尽管它们很有前途，但它们的化学复杂性和对缺陷和反位无序的敏感性限制了Heusler化合物和双钙钛矿在原型和实际设备中的研究。基础物理学的许多方面仍然没有得到很好的理解，这一事实也阻碍了进展。本项目有两个目标：(1)利用离轴超高真空溅射技术在高居里温度下沉积高质量的半金属外延薄膜和Heusler化合物的磁性隧道结，并对其结构、化学、磁性、电子、自旋极化和元素特定磁矩进行表征；(2)生长半金属双钙钛矿单晶。这种晶体的可用性将使研究其固有的自旋极化和磁输运性质成为可能。这些材料的真正前景只能通过将内在特性与源于结构和化学不均匀性的外在贡献分开来评估。该项目的目标是建立将半金属材料纳入自旋电子器件所需的科学和技术基础。这项国际合作结合了实现用于自旋电子学的半金属铁磁体的承诺所需的集体和互补专业知识。高自旋极化铁磁体在室温下的应用将为计算机革命奠定基础。此外，这项工作将加强美国和德国社区之间的联系，这将增强双方合作机构的研究基础设施。最后，科学挑战以及研究项目的跨学科和国际性质将为学生研究人员和初级科学家提供良好的培训。

This award supports an international collaborative research team from the Ohio State University and the Leibniz Institute (IFW) in Dresden, Germany to realize and understand half-metallicity (i.e. 100% spin polarization of conduction electrons) in Heusler compounds and double perovskites. These two families of complex materials contain the vast majority of half-metallic compounds with high Curie temperatures that hold the promise of highly spin polarized transport at room temperature. To advance both our fundamental understanding as well as the technological promise of spin-polarized transport in these two families, this partnership brings together complementary expertise in high-quality epitaxial film deposition of complex materials and spin polarization measurements at the Ohio State University and single-crystal growth of these materials using the state-of-the-art facilities at the Leibniz Institute in Germany. Despite their promise, their chemical complexity and sensitivity to defects and antisite disorder has limited studies of Heusler compounds and double perovskites in prototype and real devices. Progress is also hindered by the fact that many aspects of the fundamental physics are still not well understood. This project has two aims: (1) deposit high quality, half-metallic epitaxial films and magnetic tunnel junctions of Heusler compounds with high Curie temperatures using off-axis ultrahigh vacuum sputtering, coupled with characterization of their structural, chemical, magnetic, electronic, spin polarization, and element-specific magnetic moments; (2) grow single crystals of half-metallic double perovskites. Availability of such crystals will enable investigations of their intrinsic spin polarization and magnetotransport properties. The true promise of these materials can only be assessed by separating intrinsic properties from extrinsic contributions originating from structural and chemical inhomogeneity. The goal of this project is to establish the scientific and technical foundations needed to incorporate half metallic materials in spintronic devices.This international collaboration combines the collective and complementary expertise needed to realize the promise of half-metallic ferromagnets for use in spintronics. The availability of highly spin-polarized ferromagnets for room temperature applications will establish a groundwork that has the potential to revolutionize computing. In addition, this effort will strengthen the ties between US and German communities that will enhance the research infrastructure of both partner institutions. Finally, the scientific challenges, as well as the interdisciplinary and international nature of the research program will provide excellent training for the student researchers and junior scientists.