Magnetic properties of Fe(2-x)RuxZr system (abstract)

Pseudobinary systems of the type Fe(2-x)MxZr (M=transition metal) have been studied extensively for their typical magnetic properties. The common features of such systems are a breakdown of magnetic order and change in crystal structure from cubic C15 (Cu2Mg) type to hexagonal C14 (MgZn2 type) with a variation in concentration (x). The origin of the structural change is not very clear. The Fe moment is thought to be influenced by the near neighbor environment and variation in electronic structure. The present investigation involving the substitution of Fe with isoelectronic Ru assumes importance in light of this and complements the previous reported work. We find that for x<0.5 the structure is C15. For x=0.6, a structural transition to C14 type takes place. The structural transition in the case of Ru occurs at x=0.5 as against values between 0.2 and 0.4 reported for similar studies with other transition metals like V, Cr, and Mn. There seems to be a clear indication of electronic influence on the structural change. In the case of V, which has five outer electrons, the structural change occurs at a relatively low substitution of x=0.2, whereas in the case of Ru, which has eight outer electrons, the structural change occurs at x=0.5. For x=0.1 to 0.3, the samples show a behavior similar to that of Fe2Zr, which is a ferromagnet with a saturation moment of 1.7 Bohr magnetron/Fe atom at 5 K. In the case of x=0.4, however, the saturation moment undergoes a sharp fall to 1.1 Bohr magnetron. Moreover, x=0.4 shows re-entrant behavior with a Tc of about 325 K and a spin freezing temperature of 130 K. copyright 1997 American Institute of Physics