Ultrasonic Attenuation in Magnetite at Low Temperatures

抄録

The ultrasonic attenuation coefficients in magnetite crystals were measured over the temperature range of 4.2°K–300°K and two kinds of attenuation peaks were observed below the transformation temperature of ionic ordering. The attenuation is attributable to the relaxed electron diffusion between Fe²⁺ and Fe³⁺ ions on the octahedral sites in the ordered lattice of magnetite. The electron diffusion processes are classified into the single electron process and the coupled transition. The activation energy of the former process is determined to be 0.055 ev and the latter 0.36 ev.