Structure And Magnetic Properties Of REAlX(RE=Rare Earth;X=Ge,Si) Compounds

As a new spintronics material,Weyl semi-metal has both conductivity and insulation,so it has a wide application prospect and rapid research progress.As a new type of Weyl semi-metal,REAlGe has the characteristics of type ? and type ? Weyl semi-metal,so it has become a research hot-spot of spintronics materials.REAlX(RE=Nd,Sm;X=Ge,Si),containing rare earth elements,semiconductor elements and ?A element Al,through REAlX(RE=Nd,Sm;The structure and magnetic properties of X=Ge,Si)alloy compounds were studied,and the phase formation and magnetic energy variation of REAlX semi-metal were obtained.In this paper,several polycrystalline samples of REAlX(RE=Nd,Sm;X=Ge,Si)system were prepared by non-consumable vacuum arc furnace in high purity argon atmosphere.TREOR software was used to index the diffraction peaks of REAlX(RE=Nd,Sm;X=Ge,Si)series to provide lattice parameters and cell volume data for further refinement of their structures with Rietveld.SQUID-VSM,a high sensitivity magnetic measurement system,was used to test the curves of thermal magnetism(M-T)and magnetization characteristics(M-H)of the samples.According to the test and the analysis of test data,the phase structure of REAlX(RE=Nd,Sm;X=Ge,Si)series is the body-centered tetragonal structure of I41md.In each cell,the RE and Al atoms occupy two non-equivalent crystal positions of 4a(0,0,z),the semiconductor atoms Si and Ge atoms occupy 4a(0,0,0)crystal positions.REAlX consists of alternating stack of A/B layers arranged by X3,A13,and RE3 isosceles triangles ? in A layer/RE3,X3,and A13 reversal isosceles triangle in B layer along a axial direction.The noncentersymmetric structure is formed by ? and? in A and B layers.The double tetrahedrons with common vertex can be built by connecting the rare earth atoms in RE3 ? and RE3 ? with inversion symmetry,this noncentersymmetric structure of RE3 ? and RE3 ? is suggested to be relative to the magnetic responses.Because of the lack of space inversion symmetry,a non-centrosymmetric structure is formed,thereby making it easy to form a Weyl point,which may cause a special magnetic correlation.Scanning electron microscope showed the microstructure of REAlX(RE=Nd,Sm;X=Si,Ge):the particle size of the samples was evenly distributed and there was no agglomeration phenomenon.After energy spectrum analysis,it was found that the actual atomic ratio of elements in each sample was almost 1:1:1.The study of thermomagnetic characteristics shows that the REAlX(RE=Nd,Sm;X=Ge,Si)series show spin glass and antiferromagnetic characteristics respectively,which are derived from the interaction between two isosceles triangles ???-??composed of RE3 in opposite directions.Paramagnetic region obeys Van Vleck paramagnetic characteristics.The effective magnetic moment mainly comes from trivalent rare earth ions.In the end,the paper points out the problems and the concept of improvement in this paper.