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Magneto-optical Kerr effect with non-uniform optical polarisation

具有非均匀光学偏振的磁光克尔效应

基本信息

批准号：
EP/H044922/1
负责人：
Daniel Allwood
金额：
$ 18.99万
依托单位：
University of Sheffield
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FH044922%2F1
关键词：
Magneto optical Kerr effect non

项目摘要

The magneto-optical Kerr effect (MOKE) is widely used to characterise the magnetic behaviour or state of materials. Uniform beam polarisations are invariably used in MOKE measurements, whether as a parallel beam for thin film measurements or a focussed beam for measurements of small magnetic structures. Observing MOKE from in-plane magnetisation requires an oblique angle of incidence, with higher signals generally obtained with larger angles of incidence. This leads to a compromise being reached between spatial resolution and signal. Tightly focussed light beams are not purely transverse and can have a component of longitudinal electric field in the vicinity of the focus. Radially polarised light beams can significantly increase this effect and have a much reduced focal spot size for the longitudinal field component. We propose to use the longitudinal electric field associated with tightly focussed radially-polarised laser beams to perform normal-incidence MOKE measurements on materials with in-plane magnetisation. This will allow exquisite spatial resolution of magnetic thin films and nanostructures, plus the unprecedented ability to depth-resolve magnetisation. Optimising this will require a new framework to relate the relevant physics of MOKE with non-uniform optical polarisation. The three advantages of radial-polarisation MOKE (R-MOKE) are:1. An order of magnitude increase in the longitudinal component of electric field (which couples to the in-plane magnetisation to generate a Kerr signal)2. A reduction of the transverse spot size affording higher spatial resolution3. The unprecedented ability to depth-resolve magnetisation in MOKE measurements.

磁光克尔效应（MOKE）被广泛用于表征材料的磁性行为或磁性状态。均匀的光束偏振总是用于MOKE测量中，无论是作为用于薄膜测量的平行光束还是用于测量小磁性结构的聚焦光束。从面内磁化观察MOKE需要倾斜的入射角，通常以较大的入射角获得较高的信号。这导致在空间分辨率和信号之间达成折衷。紧密聚焦的光束不是纯粹的横向的，并且可以在焦点附近具有纵向电场的分量。径向偏振光束可以显著增加这种效应，并且对于纵向场分量具有大大减小的焦斑尺寸。我们建议使用与紧密聚焦的径向偏振激光束相关的纵向电场，对具有面内磁化的材料进行垂直入射MOKE测量。这将允许磁性薄膜和纳米结构的精细空间分辨率，以及前所未有的深度分辨磁化的能力。优化这一点将需要一个新的框架，将MOKE的相关物理与非均匀光学偏振联系起来。径向偏振MOKE（R-MOKE）的三个优点是：1。电场的纵向分量（其耦合到面内磁化以生成克尔信号）2的数量级增加。横向光斑尺寸的减小提供了更高的空间分辨率3。MOKE测量中前所未有的深度分辨磁化能力。