Seminário Extra: Magnetic Metamaterials for Millimetre-Wave Devices

Devices operating at millimetre-wave frequencies are widely used in communication and signal processing system. During the last decades, we have witnessed incredible progress in high frequency semiconductor electronics. However, despite an increased use of millimetre wave technology there is still a large gap of advances in structures working at high GHz frequencies. Some of the developments in this frequency rage have employed resonances in ferromagnetic materials. One problem with most of these materials is that they generally require large magnetic fields to obtain higher operational frequencies. Here, I will discuss magnetic metamaterials which can be used to engineer these resonances at particular frequencies and with greater field tunability. These are based on the properties of natural hyperbolic media; and these have recently enabled a series of advances in optics, which will also be discussed. We based our hyperbolic metamaterial on spin canting in antiferromagnets and by creating artificial magnetic multi-layers it is possible to achieve frequency tunability of 30 GHz with external fields smaller than 500 Oe. These structures have unique features in microwave waveguides that act as, for example, tunable band-pass and band-stop filters.