Skyrmion Dynamics At Ferroelectric/Ferromagnetic Interface

Skyrmion is a kind of topological soliton associated with baryons proposed by Tony Skyrme in the 1960 s.Since skyrmion was observed in the chiral material such as MnSi by Mühlbauer et al in 2009,it has received a great of attention not only because of the great potential in the spin electronic devices but also it's profound physical meaning in theory.Especially after the successful implementation of skyrmion dynamics using electric field in the multiferroic compound Cu2OSeO3 by Seki et al,the dynamic evolution of skyrmion in multiferroic materials has attracted more and more interests.However,due to the limitation of the volume,power consumption,and the defect of weak magnetization response in the single phase multiferroic materials,the electric field controllable skyrmion is hardly of any help when considering practical application.Therefore,our paper would present composite multiferroic material to break through the above limitation,based on the theoretical analysis of skyrmion dynamic at ferromagnetic/ferroelectric interface,laying an important foundation for the application of electric field control of skyrmion.Considering ferroelectric/ferromagnetic(FE/FM)composite heterostructures,we find that the strain-mediated magnetoelectric coupling and the ferroelectric field effect caused by the interface charge screening would provide a strong anisotropy for the ferromagnetic layer;Furthermore,the sharp change of interfacial potential would enhance the strength of the Rashba spin-orbit coupling(Rashba SOC)and produce a considerable Dzyaloshinskii-Moriya interaction(DMI)together with the strong spin-orbit coupling existing in heavy metal ions in the ferroelectric materials.These two not only provided a sufficient condition for the generation of skyrmion,but also laid a physical foundation for the realization of skyrmion's dynamic properties because of the strength regulation in the external electric field.Based on the Monte-Carlo simulations,we have obtained the phase diagram of skyrmion as the function of magnetoelectric coupling strength ?.After analyzing it's dynamic properties carefully,we demonstrated a translational mode,a breathing mode,and a spin flip.The dynamic properties of skyrmion would be stable at high frequency,otherwise,the skyrmion configuration would decay and even disappear.And a breathing mode will be particularly obvious with the open boundary condition due to the influence of boundary potential.The skyrmion dynamics could be accelerated under the regulation of a weak Rashba SOC,but falls into disorder because of the slow evolution of skyrmion compared to a strong Rashba SOC known by the studies of different DMI.The crescent pattern of the horizontal component permeability and the annular pattern of the vertical component permeability provide us a new way for the research and experimental exploration of skyrmion by the magnetic dynamics analysis under microwave electric field.