  We investigate the influence of the vortex chirality on the magnetization
processes of a magnetostatically coupled pair of magnetic disks. The magnetic
vortices with opposite chiralities are realized by introducing asymmetry into
the disks. The motion of the paired vortices are studied by measuring the
magnetoresistance with lock-in resistance bridge technique. The vortex
annihilation process is found to depend on the moving directions of the
magnetic vorticies. The experimental results are well reproduced by the
micromagnetic simulation.
