THE EFFECT OF MANGANESE ON MAGNETIC-PROPERTIES AND ATOMIC AND ELECTRONIC-STRUCTURE OF NIAL INTERMETALLIC COMPOUNDS

Magnetic properties, atomic and electronic structures of Ni50-xAl50Mnx (x = 1,3,5,7,10) and Ni50Al50-xMnx (x = 5, 10) compounds were studied by means of magnetic susceptibility and Al-27 nuclear magnetic resonance (NMR) measurements. Experimental results were compared with those obtained by computer calculations of the cluster electronic structure for atomic arrangements of Mn-impurity in both sublattices of NiAl. The role of Ni-vacancies, Mn-atoms in Ni- or Al-sublattices for observed behaviour of magnetism and NMR-parameters were determined. The formation of Ni-vacancies for Ni50-xAl50Mnx compounds in high Mn concentrations was found. The occurrence of localised magnetic moments (LMM) for Mn-atoms in antisite positions was observed. For the alloys Ni50-xAl50Mnx, LMM appeared at low concentrations of Mn and then disappeared for alloys with Mn > 3 at.%. The increase in density of states at the Fermi level was established by the substitution of Mn both Ni and Al atoms.