Magnetization and FMR studies in amorphous Fe90Zr10 and Fe70Ni20Zr10 ribbons

Abstract

We report here our high field magnetization (in fields up to 15 T, and preliminary FMR studies on amorphous Fe90−xNixZr10 with x=0 and 20. The addition of Ni remarkably modifies the magnetic properties of Fe90 Zr10 alloy which can be summarized as follows: (1) The ferromagnetic transition temperature, TC, increases from 230 to 476 K; (2) While the magnetization in Fe90Zr10 does not saturate at 4.2 K for applied fields up to 15 T with a large susceptibility χhf ≂9×10−4 Oe−1, the substitution of Ni for Fe leads to an easy saturation for a field of 1 T, which is unusual for a random magnet; (3) At 4.2 K the magnetic moment of the alloy increases from 1.48μB to 1.6μB per atom, from which the magnetic moment of Fe in the Fe–Ni–Zr alloy is estimated to be 2.3μB/atom. The FMR line width in Fe90Zr10 increases monotonically with decreasing temperature. For the x=20 alloy, the line width is found to be about 160 Oe, and the value of g is found to be 1.94. These results suggest that interpretation of the properties of Fe–Zr alloys on the basis of weak itinerant ferromagnetism should be taken with caution.