Minimization of Switching Energy in Scaledown of Nanomagnetic Devices in Fokker-Planck Approach*

Minimization of energy needed for switching of nanomagnetic devices, such as magnetic tunnel junctions (MTJ) and spin nanotorque oscillators (SNTO) is performed, relying on the procedure we developed based on Fokker-Planck approach, initiated in references [1, 2]. The procedure accounts for the controllable inducement of the interfacial anisotropy between at least one pair of the neighboring layers of the MTJ or SNTO [3], and takes into account that at least two geometric parameters of a nanomagnetic devices are affected by the scaledown. Modeling strongly suggests existence of an optimal effective anisotropy field (that is, optimal value for minimized switching energy or current), H_k^eff, which changes for a selected set of geometric scaledown parameters. The influence of the effective anisotropy field is studied in both switching regimes, (I < I_c, I > I_c). Energy density changes are calculated for various nanomagnetic device design parameters, as are the variations of the switching rate.
[1] T. Taniguchi et al., PRB 85, 184403; [2] D. M. Apalkov et al., PRB 72, 180405;
[3] A. F. Isakovic et al., in publication.