First-principles Investigation On Interfacial Magnetocrystalline Anisotropy

With the rapid development of science and technology,information storage material devices gradually tend to be miniaturized,high-density,low power consumption,non-volatile,high speed development direction.The rapid development of micro-nano electronic technology based on the degree of freedom of charge has met the bottleneck predicted by Moore's Law.Quantum control technology based on the degree of freedom of spin is expected to provide a new opportunity for the post-Moore information era,and a new discipline,spintronics,has been formed around the spin electronic control,optical control and magnetic control.The spin-orbit coupling effect?SOC?is a bridge between charge and spin,and is also an important research direction in the field of spintronics,leading to many exotic physical phenomena,such as topological insulation,spin hall effect,magnetocrystalline anisotropy and so on.The magnetocrystalline anisotropy energy?MAE?,which is closely related to the spin-orbit coupling effect,is an important parameter of magnetic materials.It determines the magnetic recording mode of magnetic materials in information storage.High vertical magnetic anisotropy material is often considered as the first choice for the development of ultra-high density memory devices.However,once the magnetocrystalline anisotropy is too high,it will inevitably lead to the increase of energy consumption.How to regulate the magnetocrystalline anisotropy has become the focus of people's attention.Among the various magnetic regulation methods,the electric field regulation mathod based on the interface magnetoelectric?ME?coupling effect has gained wide attention.The interfacial electric field stress and interfacial charge transfer in heterojunctions can be used to regulate the magnetocrystalline anisotropy.This paper takes 3d ferromagnetic Fe monolayer as an example,the magnetocrystalline anisotropy energy of Fe/SrTiO₃ and Fe/GeTe interface structures is studied by using the first principle calculation method based on density functional theory:1?We investigate the electronic and magnetic properties of Fe/SrTiO₃ interfaces,in which both the nonpolar surface SrTiO₃?001?and the polar surface SrTiO₃?110?are considered.A particular emphasis is placed on the magnetocrystalline anisotropy energy?MAE?.Compare MAE of the Fe/SrTiO₃ interfaces and the corresponding Fe monolayers,we find the Fe/SrTiO₃?001?interface decreases MAE,while the Fe/SrTiO₃?110?interface increases MAE.The interface orbital hybridization and orbital magnetic moments are detailly analyzed to understand the different interface magnetocrystalline anisotropy.Our investigation indicates that interface engineering can be an effective way to modulate the magnetic properties.2?Electric-field control of the magnetocrystalline anisotropy energy?MAE?in the FRS-based multiferroic heterostructure Fe/GeTe is investigated.When Fe is in contact with the Te-terminated surface,we find that Te atomic SOC has great influence on MAE,and the magnetization axis of the Fe monolayer can be switched from in-plane to out-of-plane by tuning the ferroelectric polarization.When the Fe monolayer is in contact with the Ge-terminated surface,Ge has less influence on MAE,and direction of the easy axis remains in-plane as the ferroelectric polarization is varied.The SOC-assisted giant ME coupling in FRS-based multiferroic heterostructures will be of great significance in the electric control of magnetism.