Spin Waves in Disordered Potentials: Interplay between Disorder, Nonlinearity, and Incoherence

无序势中的自旋波：无序、非线性和不相干之间的相互作用

• 批准号: 1407962
• 负责人: Mingzhong Wu
• 金额: $ 48.21万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1407962&HistoricalAwards=false
• 关键词: Spin; Waves; Disordered; Potentials; Interplay

Non-Technical AbstractWave theory is fundamental to physics, underlying everything from radar to fiber optics to cell phone communications. Waves occur in magnetic materials, where the magnetic spin precesses in a wave pattern, propagating energy and information. Magnetic materials are important in many technological contexts, including solid-state hard drives. In a perfectly ordered magnetic material a wave would propagate smoothly; however, real materials have disorder, imperfections that lead to localization of waves, so that information or energy gets trapped in a certain location in the material. This research seeks to understand many unanswered questions about localization of waves in disordered magnetic materials. In particular, three main questions are addressed: (1) Does coherence matter? Lasers, for example, are coherent, and spin waves can be too. (2) How does nonlinearity destroy localization? Nonlinearity means the whole is not the sum of the parts. In spin waves the strength of this effect can be controlled, and its impact on localization explored. (3) Can chaos cause delocalization? Real materials often exhibit chaos. Does chaos allow a localized wave to escape? To support this research and create tomorrow's scientists, the project provides extensive training opportunities for students at undergraduate and graduate levels, especially interdisciplinary cross-training between experimental and theoretical physics. Outreach to high schools in Colorado is accomplished through the Colorado State University "Little Shop of Physics" program, focusing on those in disadvantaged areas. Outreach to the broader scientific community occurs via organizing of scientific conferences, workshops, and symposia.Technical AbstractAnderson localization and Aubry-André localization have both attracted rather considerable interest across a number of disciplines in recent years due to their ubiquitous nature. Theoretical studies have yielded many predictions about the effects of coherence and nonlinearity on localization that are of great fundamental importance but are often controversial or debatable. The research in this project not only settles several current debates on localization, but also provides first experimental justifications to a number of theoretical predictions. As such, the project deepens the understanding of the interplay between disorder, nonlinearity, and coherence in general. Furthermore, the research enhances the understanding of spin-wave dynamics in magnetic thin films and damping processes in magnetic materials with disordered defects. Specifically, the studies make use of spin waves in yttrium iron garnet (YIG) thin film strips. Disordered potentials for spin waves are developed by two approaches: (1) the fabrication of disordered grooves on the surfaces of YIG strips and (2) the development of disordered local field variations by depositing meander lines on the YIG strips and passing electric currents through the lines. Two types of disordered potentials are considered: random potentials and quasi-periodic potentials. The former is used to study Anderson localization, while the latter is used for the study of Aubry-André localization. The research consists of both experimental and theoretical efforts. It is carried out through integral collaborations between Mingzhong Wu's experimental group at Colorado State University and Lincoln Carr's theoretical group at Colorado School of Mines. The new program has transformative impacts in view of promising potential applications of localization effects. For example, the energy density within a localized mode can be several orders of magnitude larger than that of the incident wave, and this huge field enhancement has potential applications for energy harvest, storage, and conversion. In addition to mentorship at undergraduate to graduate levels and outreach as described above, the principal investigators are jointly engaged in curriculum development, focusing on bringing up-to-date applications and experimental demonstrations into graduate core courses in electrodynamics and classical dynamical systems.

非技术的抽象波理论是物理学的基础，磁性的磁性旋转在磁性材料中，传播能量和信息。对于波浪的定位，该研究中的某个位置被捕获在材料中的某个位置例如，旋转波也可以是2）非线性如何破坏整体，而不是零件的总和。在科罗拉多州的高中，尤其是跨学科的跨学科训练。近年来，由于它们的无处不在，近年来，摘要和奥布里·安德烈的本地化都在近年来吸引了肛门阶段。在本地化方面，尽管对障碍，非线性和相干性的解释，但对磁性材料中的自旋波动的理解加深了实验性的预测，研究在Yttrium铁石榴石（YIG）薄膜条中使用自旋波。通过线的电势：前者的势力。科罗拉多州的理论小组都有有希望的本地化效应的潜在应用具有变革性的影响。 - 至日期的应用和经验，将无电的核心课程授予动力学系统的研究生核心课程。