Hybrid Magnetic Skyrmion

At present,magnetic skyrmion as a hot research topic has aroused much attention in the region of magnetism.Skyrmion is a promising candidate for magnetic memory of next generation because its ability to carry and deliver magnetic information.Compared with traditional medium of magnetic memory,skyrmion has some obvious advantages such as smaller size,stable configuration and smaller current density needed to display it.However,Skyrmion was typically found to be stable at low temperature in magnetic fields,which impedes their physical exploration and application.This thesis mainly focus on the study of increasing the stability of skyrmion,and the study of the racetrack memory based on skyrmion.We report a method called "hybrid magnetic skyrmion" to increase the stability of the skyrmion lattice utilizing micromagnetic simulation.Patterning Co nano disk array on the magnetic thin film owns DM interaction induces the interfacial exchange interaction which helps to stabilize the skyrmion lattice.The magnetic moments in nano disks arranged in vortex which are similar with the moments configuration in skyrmion,and Co has a Tc much higher than the material with DM interaction.So,the exchange interaction between the nano disks and the magnetic thin film can stable the skyrmions in a larger temperature range.However the mobility of the skyrmion was suppressed because of the pinning effect comes from the strong exchange interaction just like the artificial skyrmion lattice.To resolve this obstacle,we change the direct exchange interaction to RKKY interaction to decrease the exchange interaction by inserting a nonmagnetic layer between these two layers.We call skymrion in this structure hybrid magnetic skyrmion(HMS).And the HMS not only get a larger phase diagram but also can be driven the electrical current.Surprisingly,we found the skyrmion Hall effect is effectively suppressed in the condition of HMS.Then we construct the racetrack memory based on the HMS.In one side of the nano track,we can create a skyrmion by inject a polarized current pulse perpendicularly through a nano Co pillar.And the skyrmion can be driven by the in-plane current.Repeating this process,we can write and encode a string of information.The information can be easily detected and read in the other side of the track through the signal of skyrmion Hall effect.