Regensburg 2002 – wissenschaftliches Programm

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SYRE: Rastersonden- und Elektronenmikroskopie an Domänenstrukturen

SYRE II: HV II

SYRE II.1: Hauptvortrag

Dienstag, 12. März 2002, 10:00–10:30, H11

Lorentz-Microscopy on Ferromagnetic Domains — •Stephen McVitie — Department of Physics and Astronomy, University of Glasgow, Glasgow G12, 8QQ, United Kingdom

Lorentz microscopy is a powerful tool for investigating the magnetic structure of magnetic materials on a scale of less than 10 nm. At Glasgow we use the techniques of transmission electron microscopy to study the physical and magnetic structure of thin films in which the total film thickness is not greater than 100 nm. Specialised instruments are available which allow samples to be studied in a field free environment or with a field present to allow in-situ magnetising experiments to be performed. Whilst a number of Lorentz imaging modes are available the simple qualitative Fresnel imaging mode tends to be used to reveal the domain walls or magnetisation ripple in switching experiment. High resolution quantitative imaging showing the detailed structure of a material is gained through the differential phase contrast method which is practised on a scanning system. Examples will be given to illustrate the power of these two techniques. In the last few years simulation packages have become more readily available which allow the magnetisation states to be predicted for many systems. As Lorentz microscopy is sensitive to the magnetic induction in a sample rather than the magnetisation we have developed routines which calculate the images expected from Lorentz microscopy due to a given magnetisation state. Examples will be given which demonstrate excellent agreement between experiment and simulation.