Structure,Magnetic Properties And Half-metal Properties Of Heusler Alloys Ni_2-xSc_xMnSn And CrMnZ

The research content of spintronics breaks the bottleneck of the development of electronic information industry and makes it possible to store and process large amounts of data at high speed.Materials used in spintronics need to have high spin polarizability in order to find new materials suitable for spin injection in spintronics.Heusler alloy have been extensively studied and developed in recent years because of their high Curie temperature and high spin polarizability.In condensed state physics,it is a hotspot to find and design a new type of Heusler alloy in theory.In this paper,the first-principles method based on density functional theory is used to simulate Ni₂-based and Cr-based Heusler alloy by using Materials Studio software development in the United States.The exchange correlation potential function is in form of generalized gradient approximation?GGA?and the PBE-type.The crystal structure,electronic and magnetic properties of materials are simulated and calculated mainly by computer in order to find stable crystal structures.It can be used to guide the preparation and practical application of the experiment,and has the advantages of high efficiency and avoiding waste of resources.Ni_2-x-x Sc_x MnSn?x=0,1,2?contains two kinds of Heusler alloys,Ni₂MnSn?x=0?and Sc₂MnSn?x=2?are full-Heusler alloy and NiScMnSn?x=1?is quaternary Heusler alloy.For the ground state geometry optimization of NiScMnSn,it is found that the atomic occupancy modes with the lowest energy and the most stable structure are X₁:?3/4,3/4,3/4?;X₂:?1/2,1/2,1/2?;Y:1/4,1/4,1/4 and Z:?0,0,0?.On the bases of the crustal structure,the electronic and magnetic properties were analyzed.The electronic properties and magnetic sources of the three materials were analyzed.It is found that the magnetic sources of Ni₂MnSn and NiScMnSn are the energy level splitting of the Mn-3d state.The magnetism of Sc₂MnSn comes from the energy level splitting of the Mn-3d state and the hybridization between the Mn-3d and the Ni-3d state.In the half-Heusler alloy CrMnZ?Z=P,As,Sb?,the calculation of its energy shows that they can be synthesized at room temperature and are all semi-metallic antiferromagnets.The spin polarizability of all three materials can reach 100%?or close to100%?.According to the analysis of the variation curve of magnetic moment with lattice constant and density of states,the magnetic properties of three materials are derived from the strong hybridization between Cr-3d and Mn-3d states,and the trend of Cr and Mn is anti-parallel.Therefore,the three materials are all semi-metallic antiferromagnets.Within a certain range of lattice constants,the band gap structure near the fermi plane shows obvious band gap,and the band gap widths at equilibrium states are as high as 0.728,0.974 and 0.852eV,respectively.All three materials have certain practical application value.