  Electric control of multiple domain walls (DWs) motion is demonstrated by
Pt/Co/Pt nanotracks with perpendicular magnetic anisotropy. Due to the weak
microstructural disorders with small DW propagation field, the purely
current-driven DW motion is achieved in the creep regime at current densities
less than 10^7 A/cm^2 at room temperature. It is confirmed that by use of a
scanning magneto-optical Kerr effect microscope, several DWs are simultaneously
and identically displaced by the same distance in the same direction. Utilizing
such DWs motion, we succeed to realize random bits writing and transferring as
a device prototype of four-bit shift registers.
