High magnetic permeability of ε-GaxFe2-xO3 magnets in the millimeter wave region

In this study, the magnetic permeability of a series of metal substituted epsilon-Fe2O3 was first measured. The electromagnetic wave absorption properties were measured in the region of 50-75 GHz (V band), and the materials exhibited absorption peaks at 64 GHz (epsilon-Ga0.51Fe1.49O3), 59 GHz (epsilon-Ga0.56Fe1.44O3), and 55 GHz (epsilon-Ga0.61Fe1.39O3). From the reflectance and transmittance measurements, the magnetic permeability (mu'-j mu '') and dielectric constant (epsilon'-j epsilon '') of epsilon-GaxFe2-xO3 were evaluated. The mu '' values of epsilon-GaxFe2-xO3 are the highest values among reported magnetic millimeter wave absorbers in the V-band region. (C) 2010 American Institute of Physics. [doi:10.1063/1.3367889]