A model for the behavior of magnetic tunnel junctions

A magnetic tunnel junction is a device that changes its resistance with an applied magnetic field. A typical tunnel junction consists of two magnetic electrodes separated by an insulating layer. One electrode usually has a lower magnetic coercivity that allows the junction to have two configurations: a configuration in which the orientations of the magnetizations is parallel and one that is antiparallel. The antiparallel configuration is found to have a higher resistance than the parallel configuration. The theory most often used for magnetic tunnel junctions is the Simmons model. This model attempts to explain the common current voltage characteristics of the junction. However this model does not account for the magnetic properties of the tunnel junction, therefore, a new theoretical model for the properties of the magnetic tunnel junction is formulated from first principle calculations. The new model emphasizes the density of states of the magnetic electrodes, tunneling probability through an insulating layer, and the magnetic effects on the tunnel junction. Equations for the current density, resistance area product, and the magnetoresistance are formulated. The new theoretical model shows a better fit to the experimental data than the widely used Simmons model