  Magnetic vortices are characterized by the senses of in-plane magnetization
chirality and by the polarity of the vortex core. The electrical control of
vortex polarity and chirality is highly demanded not only for fundamental
understanding on spin dynamics in nano-disks under different circumstances, but
also for technological applications, such as magnetic non-volatile memories and
spin torque oscillators for neuromorphic computing. Here we report a novel
approach that enables one to electrically control both the vortex chirality and
polarity with low energy consumption. Thorough micromagnetic simulations, we
show that in thin nano-disks of diameter larger than 160 nm, with the presence
of current-induced Oersted field, the dynamic transformation of the edge
solitons is able to efficiently switch both vortex chirality and polarity with
low current under certain circumstances. We then developed an approach to
directly write any of the four vortex states by electrical current pulses from
a random state. We further investigated the switching phase diagram as a
function of disk diameters. The results show that the switching process is
highly size-dependent. As disk diameter is smaller than 160 nm, the switch of
VC chirality and polarity always takes place at the same time, resulting in an
unchanged handedness before and after switch. Furthermore, the critical switch
current can be as low as 3 x 10^6 A/cm^2 , indicating a possible way for low
current switch of vortex chirality in small disks.
