Microwave resonance phenomena in magnitite

The microwave resonance technique of L. R. Bickford, Jr.¹ of this laboratory is being used in a further study of single crystals of magnetite (Fe₃O₄). His measurements were made using 1.25 and 3.3 cm microwaves on both natural and synthetic single crystals from room temperature to -190°C. These measurements are being extended to lower temperatures using, synthetic crystals and 1.25 cm microwaves. Magnetite is known to undergo a transition at approximately -160°C characterized by anomalous effects in the specific heat, electrical conductivity, and magnetization.