EFFECT OF RU ADDITION TO NI ON THE ELECTRONIC-STRUCTURE AND MAGNETIC-PROPERTIES

Band-structure calculations based on the Korringa-Kohn-Rostoker cohere nt-potential approximation method are used to study the electronic str ucture and magnetic properties of FCC Ni-Ru alloy with a Ru concentrat ion of 20 at.%. The results show that the ruthenium is ferromagnetic i n Ni with a moment of about 0.6 mu(B) in the low-Ru-concentration regi on. The density of states calculated in the paramagnetic state shows t hat the strong d-d hybridization between Ni and Ru causes spin splitti ng of Ru, which is similar to the BCC Fe-Ru alloy. However, the local magnetic moment of Ru in the FCC Ni-Fu alloy drops abruptly as the Ru concentration increases. It is due to the non-magnetic character of FC C Ru, although BCC Ru is ferromagnetic. We clarified the reason why th e average magnetic moment of the FCC Ni-Ru alloy drastically decreases on Ru addition.