MSE Seminar Series: Michael Hill
Friday, October 14, 2016
Room 2108, Chemical and Nuclear Engineering Building
Enhanced Dielectric Constant Ferrimagnetic Oxides for Miniaturized Isolator and Circulator Devices
Novel magnetic garnets based on the system Bi1.4Y1.6-x-2yCa(x-2y)Fe5-x-y-zZrxVyAlzO12 enable the miniaturization of isolator and circulator designs based on the higher dielectric constant of the bismuth based ferrite relative to the yttrium based counterparts. Although bismuth based magnetic garnets have been known for some time, these current compositions and novel processing techniques allow for much lower dielectric and magnetic losses than had been previously reported for bismuth containing garnets. The dielectric constant of the bismuth substituted garnets is close to 30 as compared with dielectric constants near 15 for the bismuth free material. Compositions have been developed where this dielectric constant can be pushed to above 35. These materials may be modified by vanadium and aluminum doping to achieve a range of saturation magnetizations from 1900 to 400 gauss. This enables a range of devices to be manufactured including below-resonance isolators and tunable filters.