Research On The Structural,Magnetic,Half-metallic And Mechanical Properties Of Heusler Alloys Cr₂MnZ And Mn₂VZ

Spintronics,developed on the basis of traditional electronics in combination with quantum mechanics,is mainly employed to process and analyze the electronic spins of materials,so as to obtain distinguished physical properties.Half-metal magnet belongs to one of the key fields of spintronics.Some Heusler alloys diaplay high spin polarizability and Curie temperatures.That is,these alloys might exhibit half-metallism at room tempreture,which make them be ideal candidates for spin-polarized electron injection sources.Therefore,it is great significant to investigate novel Heusler alloys for spintronics devices.In this work,the first-principles methods are employed to calculate the structural,magnetic,half-metallic,and mechanical properties of full-Heusler alloys Cr₂MnZ?Z=P,As,Sb?and Mn₂VZ?Z=P,As,Sb,Bi?.Also,the half-metallism of some alloys are analyzed in details.The main results are as follows:1.The most stable structure of Cr₂MnZ alloy is obtained by adopting Hg₂CuTi-type one.The total magnetic moment of Cr₂MnP is close to 0?_B,which is indicates of the antiferromagnetism for this alloy.Such is caused by the antiparallel arrangement of the magnetic moment from magnetic atoms.The electron density of states near the Fermi level arise mainly from the 3-d electrons superposition of Cr₁,Cr₂ and Mn atoms.So Cr₂MnP is considered to be a near half-metal antiferromagnet.Besides,the total magnetic moment of Cr₂MnAs is 0?_B and the spin polarization rate,100%.The magnetism mainly comes from the hybrid mixture between the Cr₂-3d orbital and the Mn-3d states due to energy level splitting.This alloy is determined as an antiferromagnetic half-metal one.The total magnetic moment of Cr₂MnSb is about-2?_B,and the magnetism is derived from the hybrid superposition of Cr₁-3d,Cr₂-3d and Mn-3d near the Fermi level.This alloys is thought as a common ferrimagnet.2.The most stable structure of Mn₂VZ alloy is correspondent to Cu₂MnAl-type one.The total magnetic moments of both Mn₂VP and Mn₂VAs are 0?_B.The band structures and the density of states show that they are non-magnetic metals.While,the total magnetic moment of Mn₂VBi is-2?_B,and the magnetism mainly comes from the energy splitting of V-3d near Fermi level.This alloy is determined as the common ferrimagnet.The total magnetic moment of Mn₂VSb with type 3 occupancy is 0?_B,and the magnetism mainly comes from the hybrid mixing between Mn₂-3d and V-3d states.The study of the band structure and the density of states reveals that the alloy is a half-metallic antiferromagnet.3.In terms of mechanical properties,both Cr₂MnZ?Z=P,As?and Mn₂VZ?Z=P,As,Sb?alloys can all meet mechanical stability.The calculation results of elastic modulus reveal that Cr₂MnZ?Z=P,As?and Mn₂VZ?Z=P,As,Sb?alloys should belong to all high-strength brittle materials.