Noncollinear magnetic structures: A possible cause for current-induced switching

Current induced switching in Co∕Cu∕Co trilayers is described in terms of ab initio determined magnetic twisting energies and corresponding sheet resistances. In viewing the twisting energy as an energy flux the characteristic time thereof is evaluated by means of the Landau–Lifshitz–Gilbert equation using ab initio parameters. The obtained switching times are in very good agreement with available experimental data. In terms of the calculated currents, scalar quantities since a classical Ohm’s law is applied, critical currents needed to switch magnetic configurations from parallel to antiparallel and vice versa can unambiguously be defined. It is found that the magnetoresistance viewed as a function of the current is essentially determined by the twisting energy as a function of the relative angle between the orientations of the magnetization in the magnetic slabs, which in turn can also explain in particular cases the fact that after having switched off the current the system remains in the switched magnetic configuration. For all ab initio type calculations the fully relativistic screened Korringa–Kohn–Rostoker method and the corresponding Kubo–Greenwood equation in the context of density functional theory are applied.