METALLIC MAGNETISM IN AMORPHOUS TM-Y (TM=MN, FE, CO, NI) ALLOYS

Systematic variations of magnetic properties in amorphous TM-Y (TM=Mn, Fe, Co, Ni) alloys are investigated on the basis of a finite temperat ure theory of amorphous metallic magnetism which takes into account bo th thermal spin fluctuations and the fluctuations due to structural an d configurations disorder. It is shown that the magnetic phase diagram s calculated in the most random atomic configuration explain qualitati vely the spinglass (SG) in Mn-Y, the SG ferromagnetism (F) transition in Fe-Y, and the F-paramagnetism transition in Co-Y and Ni-Y alloys. M agnetization vs concentration curves and susceptibility vs concentrati on curves as well as the effective Bohr magneton numbers are also show n to be explained qualitatively or semi-quantitatively by the theory. Their miscroscopic mechanisms are elucidated by means of their electro nic structures, magnetic couplings, and atomic short range order. It i s found that the magnetism in Fe-Y and Mn-Y amorphous alloys is strong ly influenced by the atomic short range order, The result explains dif ferent magnetic phase diagrams in amorphous Fe-Y alloys and experiment al SG transition temperatures in amorphous Mn-Y alloys.