Magnetic properties of mechanically alloyed Fe100-xZrx (20 ≤ x ≤ 35) powder

Structural, kinetic and magnetic properties of amorphous/non-equilibrium solid solution powders of Fe100-x Zr-x (20 <= x <= 35) prepared by the mechanical alloying process are reported here. Magnetic properties of the as-milled powders have been investigated as functions of the Zr concentration, applied magnetic field, relaxation time and temperature. As the Zr concentration is increased in Fe100-x Zr-x, the activation energy of Fe-Zr crystallization increases, whereas the saturation magnetization and effective magnetic anisotropy show oscillatory variation. Temperature dependent field-cooled and zero-field-cooled (ZFC) magnetization measurements show the presence of spin-glass like phase at low temperature even at an applied magnetic field of 1 T. Thermomagnetic behaviour of the samples strongly depends on the strength of the external applied field. Magnetic relaxation measurements carried out at different temperatures under ZFC condition show that the magnetization relaxes slowly with time in a logarithmic manner up to 10(3) s. This slow magnetic relaxation is attributed to stress induced effective anisotropy that sets the energy of the domain walls and frustration resulting from the co-existence of ferromagnetic and finite antiferromagnetic interactions.