Magnetic properties and non-fermi liquid behaviour in mechanically alloyed FeCu

Abstract

FexCu100−x alloys where x (wt%) = 25, 35, 50, 65, and 75 were prepared via mechanical alloying. Microstructural characterization revealed a single-phase face-centered cubic structure for a wide range of compositions. Atomic volumes were estimated from measured lattice parameters suggesting a high volume state consistent with Weiss model predictions of the ferromagnetic ground state. Saturation magnetic moments at 2 K monotonically decreased from 2.28 μB/Fe for starting Fe powder to 0.65 μB/Fe in Fe25Cu75 alloy. Samples with Fe content higher than 35% exhibited magnetic transition temperatures (Tc) higher than 350 K. On the other hand, the Fe25Cu75 sample exhibit a Tc around 250 K as determined from the gradient method. According to Banerjee's criterion, the magnetic transition is determined to be second order for the Fe25Cu75 alloy. Moreover, modified Arrott plots were used to reveal the critical behavior of the Fe25Cu75. Temperature dependencies of the resistivity were measured for all samples. At low temperatures, the Fe25Cu75 alloy exhibited T3/2 dependence of the resistivity. At higher temperatures (100–300 K) all mechanically alloyed FeCu exhibited unusual T linear dependence resistivity. Such behavior is often called “strange metallicity” or non-Fermi Liquid behavior. The possible origin of such behavior was also discussed.