Magnetization Switching in a Small Disk with Shape Anisotropy

We study the precessional switching of a single domain, uniaxial magnetic disk with shape anisotropy by the micromagnetic simulation. The results show that magnetic switching can be driven by a smaller magnetic field pulse in an elliptic disk with its long semiaxis perpendicular to the easy axis than in a circular disk. The shape anisotropy can change the height of the energy barrier, thus we may obtain an optimal fast magnetization switching by tuning the aspect ratio of the disk under the thermal stability condition. The switching behavior of the elliptic and circular disks is studied in detail. It is found that only properly choosing the pulse amplitude and duration can realize the fast precessional switching.