EAPSI: Making small, low loss, metallic-magnetic heterostructures for next generation devices

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Magnetic systems are valuable in the microwave frequency range for a number of device applications useful for many communications and radar systems. Applications include isolators and other signal processing devices. Isolators specifically necessitate magnetic materials to create nonreciprocal propagation, i.e. a signal is allowed to propagate in one direction through a signal line but the reverse direction is blocked. Decreasing the size of the signal line components is necessary to move toward microchip production of components. One of the limitations to decreasing the size of the magnetic components is the large power losses inherent in metallic structures. There have been a number of proposals to limit the power losses in small magnetic systems including using non-metallic magnets. This project will model a structure with a grating of metallic-magnetic and non-metallic materials to decrease power losses. The magnetic structure will be fabricated at Dr. Adeyeye's lab at the National University of Singapore, one of the leading labs for magnetic nanofabrication, and experimental measurements will be taken. Experimental and theoretical results will then be compared.Metallic films generate eddy currents in the presence of microwave fields. By using a grating rather than a continuous metallic film eddy current losses can be significantly reduced. The goal of this project is to develop a theoretical model using analytical techniques as well as numerical simulations, such as effective medium theory and finite element modeling, to predict the effect of adding a dielectric and metallic-magnetic grating structure into a waveguide. A number of different orientations of grating, magnetization direction and polarization will be analyzed and optimized for nonreciprocal propagation with low losses. This NSF EAPSI award is funded in collaboration with the National Research Foundation of Singapore.