"Neutron Scattering, Transport, and Dilatometry Measurements of Magnetic Materials"

“磁性材料的中子散射、传输和膨胀测量”

• 批准号: 249706-2012
• 负责人: Adams, Carl
• 金额: $ 1.55万
• 依托单位: St. Francis Xavier University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=524765
• 关键词: Neutron; Scattering; Transport; Dilatometry; Measurements

A very large fraction of our modern technology is based on materials and their properties, e.g., microprocessors, computer hard drives, light-emitting diodes. These materials allow for cost-effective, reliable devices. The useful properties are often based on some fundamental physics in the system. In the case of computer hard drives, a very small part of the drive acts as a permanent magnet, whose polarity can be switched by a write head and measured by a read head at extremely high speeds. The proposed research focuses on magnetic materials, that order in a large number of ways, often in a way that is more exotic than the computer hard drive. In these cases, we are still trying to figure out the details of the ordering and how it comes about. Understanding the magnetism in these systems is the primary goal of this research. This is important from a fundamental viewpoint, but also for possible applications. In many cases, these systems can undergo large changes of ordering with very small changes in temperature, magnetic field, or by adding dopants. In one of the materials, the magnetism can almost disappear by forming pairs of oppositely aligned magnets. In another, a change in magnetism makes a big change in the electrical conductivity, like a magnetic switch. Another material has a spiral type of order that is related to materials that do not have any electrical resistance. The research involves neutron scattering, which gives a lot of information about magnetism on an atom by atom or electron by electron scale, but is carried out at very large facilities. There are also measurements of the electrical resistance and direct measurements of sample expansion using sensitive equipment.

我们现代技术的很大一部分是基于材料及其特性，例如微处理器、计算机硬盘驱动器、发光二极管。这些材料可以制造出性价比高、可靠的设备。有用的性质通常基于系统中的一些基本物理。在计算机硬盘驱动器的情况下，驱动器的一小部分充当永久磁铁，其极性可以由写磁头切换，并以极高的速度由读磁头测量。这项拟议中的研究重点放在磁性材料上，这种排序有很多种方式，通常比计算机硬盘驱动器更具异国情调。在这些情况下，我们仍在努力弄清楚订单的细节以及它是如何产生的。了解这些系统中的磁性是本研究的主要目的。从根本上讲，这一点很重要，但对于可能的应用也是如此。在许多情况下，这些系统可以经历很大的有序性变化，而温度、磁场的变化很小，或者通过添加掺杂剂。在其中一种材料中，通过形成一对相对排列的磁体，磁性几乎可以消失。在另一种情况下，磁性的变化会使导电性发生很大的变化，就像磁开关一样。另一种材料具有螺旋类型的有序，这与没有任何电阻的材料有关。这项研究涉及中子散射，它提供了许多关于原子对原子的磁性或电子对电子的磁性的信息，但是在非常大的设备上进行的。还有测量电阻和使用敏感设备直接测量样品膨胀。