Phase-field simulation of magnetic double-hole nanoring and its application in random storage

As an ideal high-density storage unit,magnetic nanorings have become a research hotspot in recent years.We can both study the evolution of microscopic state of magnetization and acquire macroscopic magnetic properties by micromagnetic simulation,which has thus been widely used.However,traditional micromagnetism cannot simulate complex stress state.Due to the introduction of microelasticity theory,the phase field method for magnetic materials can be used to calculate the coupling effect of stress and magnetic field.However,the computing model usually needs to satisfy periodic boundary condition.In this paper,the phase field simulation combined with the finite element method is employed.By using user defined element,the evolution of magnetic domain structures of the double-hole nanorings has been studied.In different diameter of the holes and external magnetic field direction,we have found seven kinds of magnetic domain evolution mechanism.Among them,the twin-vortex evolution mechanism with high stability and low demagnetization interference characteristics of advantages,has good application prospect in magnetic random-access memory(MRAM)unit.