Switching Behavior of Vortex Cores in Bilayer Nanodots by Uniform Magnetic Field Pulses

magnetic field pulses by micromagnetic simulations. The bilayer dots adopt the advantage of switching behaviors of constituent dots; the low switching field threshold of the square is still maintained and the operating switching field range is intermediate, compared to the single-layer disk and square. Besides the usual creation and subsequent annihilation of vortex-antivortex pair reported previously, subsequent antivortex or vortex and antivortex pair during the vortex core switching process can be observed in the bilayer dot with a lateral size of about 100 nm.