Study On Physical Properties Of Dilute Magnetic Doped CoTiSb Alloys And The Premartensitic Transition Strain Of NiMnGa Alloys

Heusler alloy has rich physical connotation and application prospect, and has become a great resource for scientists to explore new functional materials in various countries. In particular, ferromagnetic shape memory alloys and semi-metallic magnetic materials, which belong to Heusler structure, have shown great potential in the fields of aerospace, medical, and computer applications. The work of this dissertation is mainly research and development of a more updated ferromagnetic shape memory alloy and half metallic magnetic material, seeking to find the peculiar physical properties of the material, and their physical properties, microscopic mechanism and its functional properties launched thorough research. The main results are as follows:This paper has designed a series of Ni based single atom chains with high spin polarization is designed by using the Ni, Sb, Ti, and Sb atoms in the CoTiSb alloy. By using the first principles calculation, it is found that the Ni-Ti and Ni-Ni atomic chains showed 100% spin polarization and Ni-Sb monatomic chain out 95% of the spin polarization, in cotisb matrix formed a single spin nano column channel.It is used that the atomic number in the 23-30(V-Zn) range of elements in the CoTiSb matrix to replace a Ti atom on the chain. Z-Sb(Z=V, Cr, Mn, Fe, Co, Ni,, Cu, Zn) single atom chain was designed by this method. By calculating, we found that the V-Sb, Mn-Sb, Fe-Sb and Co-Sb monatomic chain showed the 100% spin polarization, show half metallic ferromagnetic properties; Ni-Sb atom chain out 95% of the spin polarization, the formation of the P-type conductive nano column channel. Because these nano columns have the characteristics of high spin polarization, so it is very advantageous to realize DC electric conversion magnetic storage, which can be used as a candidate material for DC electric storage.Moreover, the premartensitic transition strains of the ferromagnetic shape memory alloy Ni51.3Mn24.8Ga23.9 were studied in detail. It is found that the premartensitic transition syndrome of the alloy after annealing is the most obvious, and has maximum magnetostriction at premartensitic transition point. This shows further that Ni51.3Mn24.8Ga23.9 single crystal has a very special nature and a very good application prospects.