Study On The Structure And Magnetic Properties Of Transition Metal Clusters Supported By Two-dimensional Materials

With the increasing demand for data storage,nanometer magnetic storage is an inevitable trend in the future.Nanoscale magnetic storage requires that the storage medium can overcome the strong external thermal disturbance,which often requires the magnetic storage material to have large magnetic anisotropy energy（MAE）.The strong spin-orbit coupling effect can provide a large contribution to the MAE of materials.Small transition metal（TM）clusters have strong spin-orbit coupling effect.In order to obtain two-dimensional materials with larger MAE,two-dimensional materials supporting TM clusters is a hot research topic.In this thesis,we investigate the structural properties,electronic properties and magnetic properties of TM small clusters or TM dimers supported by two-dimensional materials by density functional theory（DFT）.Specific research work includes the following three aspects.（1）Firstly,the electronic properties and magnetic properties of Fe_mIr_n（m+n=3）clusters and Fe_mIr_n@Mg O（m+n=3）structures are calculated.In the triatomic clusters composed of Fe and Ir,MAE of Fe Ir₂ cluster can reach 23 me V,and the direction of easy magnetization axis is perpendicular to the triangular plane of the clusters.The MAE of two-dimensional Fe₂Ir@Mg O and Ir₃@Mg O structures is positive,and the MAE of Ir₃@Mg O structure can reach 21.08 me V.For Fe Ir₂@Mg O structure,the MAE of Fe Ir₂@Mg O structure is changed from-25.93 me V to 15.18 me V by increasing the vertical distance between Fe Ir₂ cluster and Mg O by 1（?）.（2）Then,the magnetic properties of the TM dimer supported on the S layer of two-dimensional Mo0.5W0.5STe are calculated.The MAE of Ru Ir@Mo_0.5W_0.5STe,Fe Os@Mo_0.5W_0.5STe and Fe Ir@Mo_0.5W_0.5STe structure are 36.5 me V,16.62 me V and 6.71 me V,respectively.The out-of-plane MAE of these three structures is mainly contributed by the coupling between the d orbitals of Ir and Os atoms.The MAE of Ru Ir@Mo_0.5W_0.5STe structure was regulated by biaxial strain.The MAE of Ru Ir@Mo_0.5W_0.5STe structure reached 50.49 me V at 2%tensile strain.The reason for the increase of MAE is that the tensile strain greatly increases the positive contribution of Ru atom to MAE of the structure.Our results indicate that 2D Ru Ir@Mo_0.5W_0.5STe is a good candidate material for magnetic storage.（3）In this thesis,3d-5d TM dimers are absorbed on the S plane of two-dimensional WSTe/In N heterojunction,where the directions of easy magnetization axis of Co Ir@WSTe/In N,Cr Pt@WSTe/In N,VIr@WSTe/In N are perpendicular to the two-dimensional material plane.The MAE of VIr@WSTe/In N structure can reach 15.49 me V.The matrix elements(d_x2_-y2,d_xy)of 5d TM atoms are the main contributors to MAE in these three structures.MAE decreases to 0 when 5%compressive strain is applied to VIr@Mo STe/In N structure.Our results will provide new ideas for the experimenter to design magnetic storage media.