Doped barium hexaferrite films for self-biased nonreciprocal components in the Q-/V-Band
Doped barium hexaferrite films prepared on alumina substrates by means of the sol-gel method, intended for utilization in self-biased nonreciprocal components, are presented in this letter. To cover a broad range of potential applications, the ferromagnetic resonant frequency (FMRF) of the material is controlled by substituting iron for scandium and aluminum. The films are deposited on coplanar waveguides to permit broadband measurements of the FMRF. As shown from measurements, the resonance can be shifted from 43.2 GHz for the undoped sample to 27.1 GHz and65.1 GHz for the films with the highest tested scandium and aluminum doping, respectively. X-ray diffraction analysis is used to evaluate the formation of secondary phases in the film. Measurement results for the hysteresis curves are obtained by vibrating sample magnetometer measurements. The results for doped and undoped samples are discussed in this letter.
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This work was supported by the German Aerospace Center (DLR) on behalf of the German Federal Ministry of Economics and Technology (BMWi) under Research Contract 50YB1305