The switching properties of a prototype system containing a spin valve as well as a tunneling junction are investigated by means of a spin-polarized fully relativistic approach. Shown are the changes in the free energy and in the magnetoresistance when the orientation of the magnetization in the magnetic slabs of such a system is changed individually. It is demonstrated that the existence of a stable and a metastable state, a necessary condition for a switching device, is essentially determined by the free energy contributions of the interfaces of that magnetic slab that is part of the spin valve as well as of the tunneling junction. Furthermore, in estimating individual switching times, it is found that most of the gain in magnetoresistance occurs within a time range of about 20 ps, the time to achieve complete switching, however, being about 1.5 ns, which is close to what is found in recent experimental results.

• Received 5 January 2011

DOI:https://doi.org/10.1103/PhysRevB.83.134413