Stoner–Wohlfarth model

The Stoner model ( called Stoner collective electron model ) is a model, named after the physicist Edmund Clifton Stoner ( 1899-1968 ), to describe the ferromagnetism of the metals iron, nickel and cobalt as an effect of the interaction on ( freely moving ) band electrons. It is a highly simplistic, phenomenological model and was first developed in 1939 by Stoner.

In the toner - model, the band structure is divided into a spin-up and spin-down orientation. In the case of a ferromagnet, the two spin- shares are shifted against each other energetically. Although this shift increases the kinetic energy, potential energy is also obtained by the exchange action, so that a total energy gain can be obtained. For this purpose, the exchange interaction ( coupling constant ) is large and the density of states near the Fermi energy must be high ( Stoner criterion):

It is not with the Stoner - Wohlfarth model to be confused by Stoner and Erich Peter Wohlfarth (1948 ) that the magnetization of an ensemble of randomly oriented small ferromagnetic single domain crystals describes. As a student of Stoner Wohlfarth also the Stoner model often applied the model in the German-speaking countries is sometimes linked to additionally with his name.