MAGNETISM AT THE NANOSCALE
Prof. E. Dan Dahlberg
There has been a renaissance in magnetism; in the area of micromagnetics (although in the modern context it should be nanomagnetics), major breakthroughs have resulted from the development of new magnetic imaging techniques . A powerful magnetic microscope is the magnetic force microscope (MFM), a variant of the atomic force microscope. One of the frontiers in magnetism being pushed back is to understand the domain structure and the magnetization reversal in nanometer sized particles. We have utilized the high resolution MFM (30 nm) we developed  to increase our fundamental understanding of magnetism on this length scale. First I will present a very elementary introduction to micromagnetics research and a description of MFM with a hands-on demonstration of the basic principles. I will then present our very recent discovery of the importance of virtual particles (vortex-antivortex pairs) in the magnetic reversal of stadia shaped particles.
1. E. Dan Dahlberg and Jian-Gian Zhu, Physics Today 48, 34 April 1995.
2. George D. Skidmore, Sheryl Foss, and E. Dan Dahlberg, Appl. Phys. Lett.
71, 3293-3295 (1997).