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Micromagnetism - some current challenges faced by experimentalists

Date: 
Thursday 13th February 2003 - 10:00 to 11:00
Venue: 
INI Seminar Room 1
Session Title: 
Computational Electromagnetism
Abstract: 
Small magnetic structures play a crucial role in modern storage devices and sensors. To achieve ever improving performance, magnetic films with superior properties and smaller (and frequently more densely packed) magnetic elements are required. When experimenting with new magnetic systems the ideal would be to have a description of the magnetisation distribution throughout the 3-dimensional magnetic system and to understand how it evolves as a function of vector field, temperature and time. Resolution as close as possible to the atomic level, and in any event better than characteristic magnetic length scales, is also highly desirable. Despite the rapid development of existing and the introduction of new magnetic microscopy techniques over the last decade, we still fall far short of these goals. In this talk, I will give examples of some recent imaging investigations with equal emphasis on the information that they do and do not provide.

Among the topics to be discussed will be the extent to which the properties of notionally identical magnetic elements differ as a result of small differences in their physical microstructure. This can be quite complex in elements comprising a single magnetic layer but is inevitably much more so in multilayers where the detailed coupling between the layers themselves remains imperfectly understood. Further challenges arise when the elements are packed closely together as interactions between them become important. Other significant topics are the effect of thermal processes leading to property changes with time, all other parameters remaining constant. Studies of this nature relate, for example, to stability and hence the suitability of particular structures for storage purposes. At the other end of the time spectrum is the phenomenon of ultra-fast switching where it is difficult to simultaneously meet the requirements of high spatial and temporal resolution.

I will discuss how combining information gleaned from experiment and micromagnetic modelling can help to advance the subject.

University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons