STUDIES OF MAGNETIC PROPERTIES OF Ni-Mn-In-Co HEUSLER-TYPE GLASS-COATED MICROWIRES

We report on magnetic properties and structure of Heusler-type NiMnln(Co) glass-coated microwires with metallic nucleus diameters ranging from 13 up to 23 mu m and total diameters from 47 to 55 mu m by prepared by the Taylor-Ulitovsky technique. We measured temperature dependence of magnetization of as-prepared and annealed at 823 k glass-coated microwire. As-prepared glass-coated microwires are paramagnetic at room temperature exhibiting ferromagnetic ordering below 220K. Annealed NiMnln sample present Curie temperature about 240K. At room temperature all studied samples present single cubic phase with a lattice constant lattice parameters: 0.5913 nm for Ni50Mn35In15, 0.5888 nm for Ni42.5Mn37.5In12.5Co7.5 and 0.5884 nm for Ni45Mn36.5In13.5Co5. Both as-prepared and annealed microwires exhibit unusual magnetization growth in vicinity of Curie temperature and considerable difference in M(T) for field cooled and zero-field cooled dependences. Considerable dependence of magnetization on magnetic field below and in vicinity of Curie temperature can be related with two-phase structure or with the Hopkinson effect.