High frequency tunable band stop filters using antiferromagnetic films

We study the performance of a high frequency band stop filter which can work in both the microwave and infrared regions using an antiferromagnet film as the active material. We find that the band stop frequencies can be adjusted by changing the applied magnetic field or by changing the temperature. Also, the attenuation of the wave at a band stop frequency can be controlled by varying the physical parameters such as the thickness of the antiferromagnetic film or the thickness of the dielectric spacer. In addition, the attenuation is strongly dependent on the anisotropy field in the antiferromagnet. Further, the band stop filter using antiferromagnet does not have the constraints due to skin depth and conductivity losses as many of the antiferromagnets are insulators. (C) 2007 American Institute of Physics.