First-order reversal curves (FORCs)

Article By:

Acton, Gary Department of Geology, University of California, Davis, California.

Last reviewed:2012

DOI:https://doi.org/10.1036/1097-8542.YB120421

Magnetic properties can be used to determine the magnetic composition, grain size, concentration, and even the origin of a material or its magnetization, as is done in environmental and rock magnetic studies of natural materials, or to assess how synthetic materials can be exploited as media for magnetic recording or in other industries. Many of the fundamental bulk magnetic properties of a material, such as the saturation magnetization, saturation remanent magnetization, and coercivity (the field needed to demagnetize a sample), are obtained from magnetic hysteresis studies, which generally focus on the major hysteresis loop (Fig. 1). Bulk magnetic properties, however, only tell part of the story because magnetic materials are comprised of numerous microscopic magnetic domains, which are regions (for example, a submicrometer grain of magnetite) with uniform magnetization. These domains may interact with each other and often have variable magnetic properties even when the material is compositionally homogeneous. Hence rather than a single (bulk) coercivity, a material will have a distribution of coercivities and that distribution will be influenced by how each micromagnetic domain interacts with neighboring domains.

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