Muon spin rotation/relaxation/resonance in solids

固体中的μ子自旋旋转/弛豫/共振

• 批准号: 9055-2007
• 负责人: Brewer, Jess
• 金额: $ 5.06万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=389896
• 关键词: Muon; spin; rotation; relaxation; resonance

Positively charged muons (an unstable form of antimatter produced at the TRIUMF accelerator) have several exotic properties which allow them to be used to probe the electromagnetic properties of materials using techniques known as Muon Spin Rotation/Relaxation/Resonance (µSR). The only µSR facility in the Americas (and one of only two of its kind in the world) is supported by NSERC at TRIUMF, where I strive to develop and improve µSR methods and capabilities applicable to my main physics interests: Since high temperature superconductors (HTSC) were discovered in 1986-87, µSR has been an essential probe of their properties; its unique sensitivity to weak and disordered magnetism allows us to study the coexistence of magnetism and superconductivity in these important new materials, to help understand how such things can exist and to better understand their electromagnetic properties so that their use in practical devices may be hastened. As a member of the CIAR Quantum Materials program I have learned that many of the magnetic properties of HTSC are governed by the cooperative behaviour of strongly correlated electrons, which is also manifest in the magnetism of other materials, such as cobalt oxides which are candidate materials for thermoelectric devices to convert heat directly into electricity. I collaborate with Japanese scientists to study such potential applications; I also have an ongoing collaboration with Russian scientists to study insulators and semiconductors, in which a muonium (Mu) atom is often formed when a positive muon captures an electron liberated by its passage. By studying the field dependence of Mu formation, we have been able to determine the mobility of charge carriers in various materials - information vital to their use in devices. Recently we have combined the above µSR methods to study magnetic semiconductors - candidate materials for "spintronics" devices which could perform electronic logic operations and store magnetic information simultaneously. The techniques of µSR can also be applied to various fundamental physics investigations; I am active in several of these at TRIUMF, including the TWIST experiment and several studies of muonic atoms.

带正电的μ子（TRIUMF加速器产生的一种不稳定形式的反物质）具有几种奇特的特性，使它们能够使用μ子自旋旋转/弛豫/共振（µSR）技术来探测材料的电磁特性。美洲唯一的微SR设施（也是世界上仅有的两个此类设施之一）得到了TRIUMF NSERC的支持，在那里我努力开发和改进适用于我主要物理兴趣的微SR方法和能力：自1986-87年发现高温超导体（HTSC）以来，微SR一直是其性质的重要探测；它对弱磁性和无序磁性的独特敏感性使我们能够在这些重要的新材料中研究磁性和超导性的共存，以帮助理解这些东西是如何存在的，并更好地了解它们的电磁特性，以便加速它们在实际设备中的应用。作为CIAR量子材料项目的一员，我了解到HTSC的许多磁性是由强相关电子的合作行为控制的，这也体现在其他材料的磁性上，比如钴氧化物，它是热电设备将热直接转化为电的候选材料。我与日本科学家合作研究这些潜在的应用；我还在与俄罗斯科学家合作研究绝缘体和半导体，其中，当一个正介子捕获一个通过时释放的电子时，通常会形成一个介子原子。通过研究Mu形成的场依赖性，我们已经能够确定各种材料中载流子的迁移率-这对它们在设备中的使用至关重要的信息。最近，我们结合上述微SR方法来研究磁性半导体——“自旋电子学”器件的候选材料，它可以同时进行电子逻辑运算和存储磁性信息。微SR技术也可以应用于各种基础物理研究；我在TRIUMF积极参与其中的几个，包括TWIST实验和几个介子原子的研究。