Micromagnetic Simulation Of Fe/Co Single-crystalline Multilayer

With the advent of the era of big data,the exponential growth of data has put forward higher requirements for storage density and read/write speed.The discovery of GMR provides a new direction for the realization of more efficient and lower energy consumption memory devices.In the research and development process of new memory technologies and spintronic devices,the study of single crystal materials can provide a deeper understanding of the underlying physics of the corresponding system,thereby obtaining the desired properties.In this paper,the magnetic properties of Fe/Co single crystal multilayer film composite system were studied by using micromagnetic simulation.It mainly contains the following contents:In chapter 1,the working principle of several typical magnetic storage technologies、GMR、TMR are introduced.The development trend of low-dimensional magnetic materials and the main contents of this work are introduced.The second chapter briefly introduce the development and content of micromagnetic theory,also several commonly used micromagnetic simulation software are introduced.In chapter 3,the influence of Co layer thickness on the magnetic properties of Fe/Co bilayer system is studied.It was found that the magnetic moment distribution of the film has two forms:vortex state and double vortex state,and the total energy density of the vortex state is always lower than that of the double vortex state.When an external magnetic field is applied,the system exhibits two different inversion modes:quasi-uniform inversion when t _Co≤4 nm;t _Co≥5 nm,the magnetic moment is inverted by the movement of double vortex domains,and the coercive force changes regularly.The fourth chapter mainly studies the effect of shape anisotropy on the magnetic properties of Fe/Co bilayer films.With the change of short axis length 2b,the magnetic structure with the lowest energy of the system also changes.With the addition of a magnetic field,with the increase of 2b,the magnetization inversion mode also transitions from quasi-uniform inversion to magnetic moment inversion through vortex domain movement,and the coercivity decreases rapidly.Therefore,shape anisotropy can be an effective way to control the coercivity of the system.The fifth chapter studies the antiferromagnetic/ferromagnetic coupling effect.With the antiferromagnetic coupling,the magnetization inversion proceeds step by step.When the interface exchange interaction is ferromagnetic coupling,the magnetic moments of the two ferromagnetic layers are reversed synchronously under the field.The squareness of the hysteresis loop becomes higher.Through the analysis of the MR response curve,the system withσ=-0.5×10^-4J/m² has a wider linear variation region,and the sensitivity is higher than that of the system withσ=-1×10^-4 J/m².Through the above studies,the influence of these factors on the magnetic properties can be obtained.The change in the length of the short axis leads to a different magnetization structure of the film in the lowest energy state.With an external magnetic field,the thin film completes the inversion in different ways.With the same inversion mode,the coercivity changes monotonically,so the coercivity can be regulated by adjusting the thickness and shape.The research about the Fe/NM/Co three-layer film system provide some references for its application in magnetic devices based on tunnel magnetoresistance effect.