Hysteresis curves are used in many different fields of
science and engineering as a means of characterizing the magnetic properties
of natural and synthetic materials. Although a typical hysteresis curve
may consist of several hundred data points, researchers typically extract
only a few numbers from these curves. These numbers provide information
about the average magnetic properties of the material in question.
Researchers at UC-Davis have developed a technique
that allows them to determine the distribution of magnetic properties within
a material, rather than just the average value. The technique uses partial
hysteresis curves to produce a First-Order Reversal Curve (or FORC) diagram.
A FORC may provide considerably more information than a single hysteresis
curve, such as details about the composition and size distribution of the
magnetic particles and their interactions. The FORC method has been used
for studying the magnetic properties of natural geologic samples and synthetic
materials. For example, the FORC method is being used to study the magnetic properties
of the igneous oceanic crust in order to determine the source of lineated marine
magnetic anomalies as well as to study magnetic nanostructures in
multilayer thin films and advanced magnetic media.