Development of ultrathin intermetallics for giant spin Hall effects

非技术摘要：某些非磁性金属在电流通过时表现出磁铁的特性。当电流通过这些表现出所谓的自旋霍尔效应的金属时，它们可以用来控制相邻铁磁性金属的开关和其他功能特性，这些金属被三明治结构中的几个原子层去除。这种现象被称为自旋霍尔效应，在磁性数据存储(自旋电子学)中的应用是非常令人兴奋的，因为它使得纳米级磁体的电流控制开关非常有效。这个项目将寻找化学有序的金属合金，厚度可达12个原子层，预计将提供非常有效的电流控制磁性。这些金属合金将在几十个原子的厚度下合成；将研究它们的原子排列和化学转变，并将在接近绝对零度的温度下测量它们在数据存储中的功能特性，直到室温。这些改进材料的发现将对信息存储技术产生广泛影响。研究生将获得广泛的专业知识，从经典的冶金电子器件。计划与曼哈顿的K-12学校开展外联活动。技术总结：该项目将以钨(W)和其他重金属为基础，对超薄顺磁金属间化合物相进行材料搜索，这些相有可能高效地将电荷电流转化为自旋电流。理论分析表明，具有大量原子的金属间化合物相的转换效率(自旋霍尔角)可能超过目前已知的最高自旋霍尔角的钨(W)。这些实验将结合外延超薄膜沉积、高分辨率透射电子显微镜(TEM)表征、相变动力学测量以及使用射频技术创新地测量自旋霍尔效应。具有高自旋霍尔角的相的发现将产生广泛的影响，促进将自旋扭矩纳入信息存储技术。研究生将获得广泛的专业知识，从经典冶金学(微结构、相变)到薄膜级物理性质的测量(低温磁输运和铁磁共振)，再到自旋电子器件的整合。计划与曼哈顿的K-12学校开展外展活动。

Non-technical Summary:Certain nonmagnetic metals have been shown to behave like magnets when electrical current is passed through them. As electrical current is passed through these metals, which exhibit the so-called spin Hall effect, they can be used to control the switching and other functional properties of adjacent ferromagnetic metals, removed by a few atomic layers in a sandwich structure. This phenomenon, known as the spin Hall effect, is very exciting for applications in magnetic data storage ('spintronics'), since it enables very efficient current-controlled switching for nanoscale magnets. This project will search for chemically ordered metal alloys, up to a dozen atomic layers thick, which are expected to offer very efficient electrical-current control of magnetism. These metallic alloys will be synthesized at thicknesses of dozens of atoms; their atomic arrangements and chemical tranformations will be studied, and their functional properties in data storage will be measured at temperatures approaching absolute zero and up to room temperature. The discovery of these improved materials would have broad impact in information storage technology. Graduate students will gain broad expertise in topics ranging from classical metallurgy electronic devices. Outreach activities are planned with K-12 schools in Manhattan.Technical Summary:This project will conduct a materials search for ultrathin paramagnetic intermetallic phases, based on tungsten (W) and other heavy metals, which have the potential to convert charge current to spin current with high efficiency. Theoretical considerations indicate that intermetallic phases with a large number of atoms per unit cell should have a conversion efficiency (spin Hall angle) possibly in excess of that observed for tungsten (W), which currently has the highest spin Hall angle known. The experiments will combine epitaxial ultrathin film depositions, high-resolution transmission electron microscopy (TEM) characterization, measurements of phase transformation kinetics, and innovative measurements of the spin Hall effect using radio-frequency techniques. The discovery of phases with high spin Hall angles would have broad impact, facilitating the incorporation of spin torque in information storage technology. Graduate students will gain broad expertise in topics ranging from classical metallurgy (microstructure, phase transformations) to measurements of film-level physical properties (cryogenic magnetotransport and ferromagnetic resonance) to incorporation in spin electronic devices. Outreach activities are planned with K-12 schools in Manhattan.