Introduction to Research Seminar

There has been a renaissance in magnetism in the last decade or so. 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 1. 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 2 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 principle. First we will present a very elementary introduction to micromagnetics research and a description of MFM with a hands on demonstration of the basic principle. We will next discuss, in some detail, one of the magnetic materials we study, 50nm magnetite crystals (a magnetosome) grown in magnetotactic bacteria (this includes a video of the bacteria trying to find food at the end of the magnetic rainbow). At the end of the talk we will discuss the magnetic states and the magnetization reversal process in magnetosome chains and lithographically prepared stadia of the soft magnetic material, permalloy.

1. E. Dan Dahlberg and Jian-Gian Zhu, Physics Today 48, 34 April 1995.

Supported by ONR and the University of Minnesota MRSEC.