Complex permittivity and permeability of strontium ferrites at millimeter waves

Magneto-optical approach for the measurements of complex dielectric permittivity and magnetic permeability of solid and powdered strontium ferrite materials has been performed in the Q-, V-, and W-band frequency ranges. Free-space quasioptical millimeter-wave spectrometer equipped with a backward-wave oscillator as a tunable source of coherent radiation provides the transmittance spectra in transverse magnetic field up to 7.5 kOe. Frequency dependences of dielectric and magnetic parameters of strontium ferrites have been calculated by matching theoretical curves to the experimental transmittance spectra. Shifting of the ferromagnetic resonance to higher frequencies and broadening of the zone of strong absorption in magnetic field for solid ferrite materials have been observed. (C) 2006 American Institute of Physics.