Self-oriented CoFe2O4composites for non-reciprocal microwave components

Abstract

In telecommunication systems, heavy bulky magnets are used to establish the proper functioning of a circulator by ensuring the uniform orientation of the ferrite material’s magnetic moment.Thus to develop an unbiased coplanar microwave circulator, the approach based on “ferromagnetic nanowired composite substrates” was promising. The idea was to do a magnetophoretic deposition of nanocoloidal cobalt ferrite nanoparticles into porous alumina membranes and permanently orient them uniformly. Therefore, in order to check the orientation possibility of the nanoparticle, samples of magnetic thin films on glass substrates were synthetized from CoFe2 O4 nanoparticles dispersed in a silica sol-gel matrix using the dip-coating technique with and without a uniformly applied magnetic field. To investigate the magnetic behavior of the prepared samples, the Faraday rotation as a function of the applied magnetic field was measured using a spectral polarimeter. The unambiguous qualitative difference between the Faraday rotation hysteresis loops shows a large variation of coercive (μ0 Hc ) and remanent field (M r /M s ) values, thus proving the orientation of the nanoparticles.Such nanocomposite is a promising candidate for future miniature microwave circulators fabrication.