Observation of millimeter wave ferromagnetic resonance in cubic and hexagonal ferrites

Natural ferromagnetic resonance (in the absence of an externally applied DC magnetic field) has been observed at 240 GHz in a powdered magnetoplumbite suspended in a thin layer of paint. “Induced” ferromagnetic resonance has been observed at many millimeter wave frequencies in the presence of an externally applied magnetic field according to the rule: f = γ H.