MAGNETIC-PROPERTIES OF AMORPHOUS BI2DYFE5O12

Amorphous Bi2DyFe5O12 films have been prepared by rf sputtering techni que. The magnetic properties, structure and effect of annealing have b een investigated. The magnetization increases with increasing magnetic field and is not saturated at a high magnetic field of 65 kOe. In the temperature range 20 K < T < 200 K the susceptibility can be describe d by a Curie-Weiss law with a Weiss constant of theta = -15 K. The eff ective paramagnetic moment for the iron ion (4.1 mu(B)) is much smalle r than the theoretical moment (5.9 mu(B)). Above 200 K the slope in ch i-1 vs T curve changes. The Weiss constant and effective paramagnetic moment for the iron ion increase. After annealing above 600-degrees-C the amorphous samples crystallize to a single garnet phase with the ma gnetization of 21 emu/g at 1.5 K and 7.2 emu/g at 300 K, which are the same as those of the bulk Bi2DyFe5O12 garnet ferrites.