Time-Resolved Spin Dynamics in Ferromagnetic Microstructures

铁磁微结构中的时间分辨自旋动力学

• 批准号: 0406029
• 负责人: Paul Crowell
• 金额: $ 31.5万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0406029&HistoricalAwards=false
• 关键词: Time; Resolved; Spin; Dynamics; Ferromagnetic

This research program will study the spin dynamics of sub-micron ferromagnetic particles. Picosecond time-resolved Kerr microscopy will be used to study the excitation spectra and origins of spin dephasing in individual nanoparticles with simple magnetic microstructures. A comprehensive understanding of the dynamics of these systems will be developed, including connections to the important problem of spin transport. New measurements will provide information about low-lying excitations in the presence of a magnetic field, the dynamics of interacting magnetic vortices, and the response of domain walls to sub-nanosecond current pulses. The second area of research focuses on the origins of spin dephasing in smaller nanoparticles, in which the suppression of coherence by the generation of non-uniform spin-wave modes will be explored. The third problem addressed by this program will be the relationship between spin dynamics and spin transport in both metallic and semiconductor devices. The impact on magneto-electronics will be enhanced through collaborations with materials scientists as well as the training of graduate students in ultrafast techniques and nanofabrication. Small magnetic particles, with dimensions much less than one micron (a human hair has a diameter of about 25 microns), are already integrated into technologies such as computer disk drives. New electronic devices have been proposed that combine small magnetic elements with semiconductor components such as transistors. This program addresses the fundamental physics that governs the behavior of small magnetic particles, sometimes called nanoparticles, on time scales of less than a nanosecond (one billionth of a second). For comparison, a "bit" of information in a state-of-the-art computer disk can be written in about one nanosecond. The effects of shape, internal structure, and the presence of other particles will be explored using a very fast form of optical microscopy. The experiments will involve the development of new optical and microwave techniques by graduate students as well as significant collaboration with materials scientists. The development of new ultrafast magnetic devices will be investigated through interactions with other university programs as well as local industry.

该研究计划将研究亚微米铁磁颗粒的自旋动力学。 皮秒时间分辨克尔显微镜将用于研究具有简单磁性微结构的单个纳米粒子的激发光谱和自旋相移的起源。 将全面了解这些系统的动力学，包括与自旋输运这一重要问题的联系。 新的测量将提供有关磁场存在下的低层激励、相互作用的磁涡流的动力学以及磁畴壁对亚纳秒电流脉冲的响应的信息。 第二个研究领域集中于较小纳米颗粒中自旋相移的起源，其中将探索通过产生非均匀自旋波模式来抑制相干性。 该计划解决的第三个问题是金属和半导体器件中自旋动力学和自旋输运之间的关系。 通过与材料科学家的合作以及对超快技术和纳米制造研究生的培训，将增强对磁电子学的影响。尺寸远小于 1 微米（人发直径约为 25 微米）的小型磁性颗粒已被集成到计算机磁盘驱动器等技术中。 人们已经提出了将小型磁性元件与晶体管等半导体元件相结合的新型电子设备。 该程序解决了控制小磁性粒子（有时称为纳米粒子）在小于纳秒（十亿分之一秒）的时间尺度上行为的基础物理问题。 相比之下，最先进的计算机磁盘中的“位”信息可以在大约一纳秒内写入。 将使用非常快速的光学显微镜来探索形状、内部结构和其他颗粒的存在的影响。 这些实验将涉及研究生开发新的光学和微波技术以及与材料科学家的重要合作。 将通过与其他大学项目以及当地工业的互动来研究新型超快磁性设备的开发。