Overlapping-skyrmions based racetrack memory

The magnetic skyrmion is expected to be used as a binary digit of a domain motion type magnetic memory such as a racetrack memory. When two or more skyrmions are aligned on a track, a space is needed between each skyrmion. Thus, we propose the use of overlapping skyrmions for the binary. One of the overlapping skyrmion is known a biskyrmion. The biskyrmion is two overlapping skyrmions and its skyrmion number is 2. We simulate the overlapping skyrmions produced in the perpendicularly magnetized nanowire by using the micromagnetic approach. The two or more overlapping skyrmions can be stabilized in the wire. These were moved by the spin-polarized current flowing through the wire in a similar manner to the skyrmion.