Origin of thermoremanent magnetization

Some characteristics of remanent magnetization, such as grain size effect on the intensity of remanent magnetization, additivity of partial remanent magnetization, and stability against low temperature demagnetization, are studied for IRM, inverse TRM, and TRM. All the experiments seem to indicate that IRM and inverse TRM are essentially controlled by domain wall movements due to magnetostatic force, whereas TRM results from rotation of single domain magnetic moments under the influence of thermal agitation and an applied field. It is concluded that source of the main part of TRM produced just below the Curie point appears to be in very small subregions of ferromagnetic minerals which are shielded from the exchange interaction of the surrounding spins by submicroscopic grain boundaries and which behave like single domains independent of the rest of the grain.