Composition and temperature dependence of the magnetocrystalline anisotropy in Ni/sub 2+x/Mn/sub 1+y/Ga/sub 1+z/ (x+y+z=0) Heusler alloys

Summary form only given. Magnetic-field-induced strains of the order of 5% have been recently observed in single crystalline Ni/sub 2/MnGa, under the application of relatively low fields. This ferromagnetic Heusler alloy, which exists in a wide compositional range, crystallizes in the L2/sub 1/ cubic structure. On cooling from high temperatures, it undergoes a martensitic transformation to a complex uniaxial structure, that is magnetically hard. The magnetocrystalline anisotropy of this phase plays an important role in the occurrence of the observed magnetic-field-induced strains. In the present study the samples Ni/sub 2+x/Mn/sub 1-x/Ga with x=0, 0.1, 0.15 and Ni/sub 2/Mn/sub 1+y/Ga/sub 1-y/ with y = 0.06 and 0.12 were prepared. The composition dependence of their magnetic and structural transition temperatures as well as the composition and temperature dependence of the magnetocrystalline anisotropy were studied. The determination of the anisotropy field (HA) values was done by using the Singular Point Detection (SPD) technique, that is a straightforward method applied to polycrystalline materials.