PROPERTIES ON REQUEST IN SEMI-HEUSLER PHASES

Various transport and magnetic properties of semi-Heusler phases are d escribed, which arise from the particular crystallographic structure a nd narrow band phenomena. Semiconducting-to-metal cross overs are obse rved by varying the electron concentration. The onset of weak itineran t ferromagnetism often arises in the metallic state. Even in NiMnSb, w here the strong ferromagnetism results in a half metallic state below 80 K, the magnetism evolves from Heisenberg-like to itinerant by incre asing the temperature. Giant magnetoresistance effects are observed in the semiconducting rare earth compounds NiRSb. (C) 1997 Elsevier Scie nce S.A.