Artificially Structured Materials

人工结构材料

• 批准号: 9732763
• 负责人: Chia-Ling Chien
• 金额: $ 33万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9732763&HistoricalAwards=false
• 关键词: Artificially; Structured; Materials

9732763 Chien This project deals with artificially structured materials, primarily quasi two-dimensional multilayers and one-dimensional nanowire arrays. Such materials exhibit novel properties due to their geometry, the interplay between constituent materials, and the degrees of freedom in their fabrication. The multilayer work will address key questions in ferromagnetic/antiferromagnetic (FM/AF)exchange coupling and magnetic/superconducting multilayers. Thus, the materials fabrication work will address the question of whether FM/AF coupling can be established between transition metal and rare earth moments. A further topic to be investigated in detail is the spatial variation of the FM/AF coupling as the individual layers in the multilayer arrays are traversed. The magnetic/superconducting multilayers employing ferromagnetic and antiferromagnetic constituents offer an excellent opportunity to investigate the pair-breaking mechanism arising in antiferromagnetic/superconducting planer interfaces, and superconducting ground state properties expressed in junction interfaces. Novel fabrication techniques have been developed to produce bismuth nanowire arrays that have been found to exhibit very large magnetoresistance. The origins of this and related electrical transport properties remain obscure and will be further investigated. The research involves graduate students in a range of fundamental projects that also have potential for major impact on technological areas such as information storage technology and the microelectronics industry. %%% This project deals with artificially structured materials such as quasi two-dimensional multilayers and one- dimensional nanowire arrays. Such materials exhibit novel properties due to their geometry, the interplay between constituent materials, and the degrees of freedom in their fabrication. These materials are of interest from fundamental viewpoints, but additionally have important technological applications in magnetic recording readheads, wide-range magnetic field sensing devises, and field emitters for flat panel displays. The magnetic interaction between multilayers leads to a phenomenon known as exchange biasing. This exchange biasing is at the heart of the new generation of high performance magnetic recording heads. Several key questions in the nature and mechanism of exchange biasing, and materials synthesis aspects of exchange biasing, will be explored. Nanowire arrays of bismuth will be investigated to understand origins of magnetoresistance in this semi- metallic material. The arrays show promise for applications for field sensing devices. The mechanism of the large magnetoresistance is poorly understood and the influence of fabrication methods on this transport property will be systematically investigated. The research involves graduate students in a range of fundamental projects that also have potential for major impact on technological areas such as information storage technology and the microelectronics industry. ***

9732763钱这个项目涉及人工结构材料，主要是准二维多层膜和一维纳米线阵列。这类材料由于其几何形状、组成材料之间的相互作用以及制造过程中的自由度而显示出新的性质。多层膜工作将解决铁磁/反铁磁(FM/AF)交换耦合和磁/超导多层膜中的关键问题。因此，材料制备工作将解决能否在过渡金属和稀土磁矩之间建立FM/AF耦合的问题。另一个要详细研究的主题是当多层阵列中的各个层被遍历时FM/AF耦合的空间变化。采用铁磁和反铁磁成分的磁性/超导多层膜提供了一个很好的机会来研究反铁磁/超导平面界面上的对破裂机制，以及结界面上表现的超导基态性质。已经开发了新的制造技术来制造已经被发现具有非常大的磁阻的铋纳米线阵列。这一特性和相关的电传输特性的起源仍不清楚，将进一步进行调查。这项研究让研究生参与了一系列基础项目，这些项目也可能对信息存储技术和微电子行业等技术领域产生重大影响。这个项目涉及人工结构材料，如准二维多层膜和一维纳米线阵列。这类材料由于其几何形状、组成材料之间的相互作用以及制造过程中的自由度而显示出新的性质。这些材料从基本观点来看是有意义的，但另外在磁记录读取头、宽范围磁场传感设备和平板显示器的场发射器中具有重要的技术应用。多层膜之间的磁相互作用导致了一种称为交换偏置的现象。这种交换偏置是新一代高性能磁记录头的核心。将探讨交换偏置的性质和机理以及交换偏置的材料合成方面的几个关键问题。将对铋纳米线阵列进行研究，以了解这种半金属材料的磁阻起源。这些阵列显示了现场传感设备的应用前景。大磁阻的机制目前还不清楚，制备方法对其输运特性的影响将被系统地研究。这项研究让研究生参与了一系列基础项目，这些项目也可能对信息存储技术和微电子行业等技术领域产生重大影响。***