Dr. Bryen Lorenz, in collaboration with Dr. Charles Graham, Jr. from the University of Pennsylvania, entitled "Demagnetization Factors for Disk Samples of Non-ideal Soft Magnetic Materials". The article has been accepted for publication in the Journal of Applied Physics in the May, 2010 issue.
ABSTRACT: To find out whether experimental magnetometric demagnetization factors for disk samples of permalloy are valid for other magnetic materials with significant values of coercive field, such as samples of 1095 (high carbon) steel shim stock, and for cold-rolled pure nickel. The observed demagnetization factors for steel agree well with those for permalloy but the values for cold-rolled nickel do not. The criterion for agreement appears to be a hysteresis loop with straight, parallel sides up to at least half of the saturation magnetization, implying a magnetization process controlled by the magnitude of the demagnetization field.