Millimeter-Wave Faraday Rotation From Ferromagnetic Nanowires

Nickel nanowires embedded in track-etched polycarbonate membrane filters have been used to impart Faraday rotation on millimeter wave signals with frequencies of 61.25 GHz. A customized apparatus for measuring Faraday rotation was designed and built using quasi-optical components. Initial experiments were performed to ensure that the non-reciprocal polarization rotation, attributed to the Faraday effect, had direct proportionality to the strength of a static magnetic field applied in the direction of the millimeter wave propagation. Experiments were also performed to rule out the possibility of measuring reciprocal polarization rotation due to birefringence and to calculate the Faraday rotation angle in these artificial ferrites. A Verdet constant was extracted from experimental data and found to have a relatively high value of approximately 25.5 × 10 3 rad·T -1 ·m -1 .