Experimental Studies of Surface and Interface Magnetism by Spin Polarized Electron Techniques

自旋极化电子技术表面和界面磁性的实验研究

• 批准号: 0072708
• 负责人: Herbert Hopster
• 金额: $ 33万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-15 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0072708&HistoricalAwards=false
• 关键词: Experimental; Studies; Surface; Interface; Magnetism

This research program is concerned with the spin dependent scattering of low-energy electrons from magnetic surfaces, and with the magnetic structure at interfaces of ferromagnetic and antiferromagnetic materials. The role of magnons in low-energy electron scattering in magnetic materials is largely unexplored. A high-resolution electron energy loss spectrometer (EELS ) will be built and combined with a spin polarized electron source to measure these spin dependent excitations. The exchange coupling at ferromagnetic/antiferromagnetic interfaces is of current interest in a range of contexts. For example, atomic scale roughness can lead to frustration and can drive magnetic reorientation transitions of the ferromagnetic film. This project will study the temperature dependent microscopic magnetic structures in ultrathin ferromagnetic films by magnetic microscopy and complementary structural characterization by STM and AFM. Graduate students will be trained in state of the art sample preparation and characterization techniques that prepare them for research positions in academic, government or industry laboratories.%%%A new field of electronic devices based on spin dependent transport in magnetic nanostructures is currently emerging under the name of "spintronics". In these devices the electrical properties depend on the magnetic structure of magnetic materials with layer thickness of nanometers. In these magnetic materials, electrons can lose energy by exciting spin waves (magnons) in the material. These processes, currently largely unexplored experimentally, are potentially very important in determining the materials' electrical properties. In this project, electrons will be scattered off magnetic surfaces and their energy losses studied. Use of a spin polarized electron beam allows one to distinguish between magnetic and non-magnetic excitations.At interfaces of different magnetic materials the magnetism can be dominated by the magnetic coupling between the materials. This can lead to unusual magnetic properties of ultrathin magnetic films. These effects depend sensitively on the interface quality, e.g. atomic scale roughness. This program will combine magnetic microscopy and STM to study the interplay between topography and micro-magnetic structure in magnetic thin films in contact with antiferromagnetic substrates. Students will be trained in cutting-edge materials preparation and advanced measurement techniques that prepare them for academic or industrial research in Materials and Applied Physics.

本研究计划主要研究低能电子在磁性表面的自旋相关散射，以及铁磁和反铁磁材料界面处的磁性结构。磁振子在磁性材料中的低能电子散射中的作用在很大程度上还未被探索。高分辨率的电子能量损失谱仪（EELS）将建立和自旋极化电子源相结合，以测量这些自旋相关的激发。在铁磁/反铁磁界面的交换耦合是当前感兴趣的范围内的上下文。例如，原子尺度的粗糙度可导致挫折，并可驱动铁磁膜的磁重取向转变。本计画将利用磁性显微镜及扫描隧道显微镜（STM）与原子力显微镜（AFM）之互补结构表征，来研究非磁性薄膜中温度相关之微观磁性结构。研究生将接受最先进的样品制备和表征技术的培训，为他们在学术，政府或行业实验室的研究职位做好准备。%基于磁性纳米结构中的自旋相关输运的电子器件的新领域目前以“自旋电子学”的名义出现。在这些器件中，电性能取决于层厚为纳米的磁性材料的磁结构。在这些磁性材料中，电子可以通过激发材料中的自旋波（磁振子）而损失能量。这些过程，目前在很大程度上未经实验探索，在确定材料的电性能方面可能非常重要。在这个项目中，电子将从磁性表面散射，并研究它们的能量损失。自旋极化电子束的使用允许区分磁性和非磁性激发。在不同磁性材料的界面处，磁性可以由材料之间的磁耦合支配。这可能导致非磁性薄膜的不寻常的磁性。这些效应敏感地依赖于界面质量，例如原子尺度的粗糙度。本计画将结合联合收割机与扫描隧道显微镜来研究反铁磁基底上磁性薄膜的微磁结构与表面形貌之间的相互影响。 学生将接受尖端材料制备和先进测量技术的培训，为材料和应用物理的学术或工业研究做好准备。