Induction of Magnetic Accommodation Processes in Polycrystalline Yttrium Iron Garnet

Abstract
Magnetic disaccommodation phenomena are studied in YIG polycrystalline samples. The compouads were prepared by a ceramic technique and sintered at temperatures ranging from 1350°C to 1450°C in air and CO₂ atmospheres. The results are presented as isochronal spectra of the relative time variation of the initial magnetic permeability after specimen demagnetization. For samples sintered in air atmosphere, it can be observed a clear positive relaxation peak around 125 K. When the sintering temperature is increased, the amplitude of this peak decreases slightly and a new process appears at higher temperatures (around 180 K). On the contrary, a drastic change is produced when samples are resintered in CO₂ atmosphere. In this case, relaxation spectra exhibit negative peaks (accommodation processes) around 115 K. Also, the relaxation features of these processes seem to be influenced by sintering temperature. Some reasonable speculations about the mechanism responsible for this behaviour are pointed out.