Rare Earth Orthoferrite Tuning of Transmitted Waves as Natural Metamaterials.

Metamaterials display many electromagnetic properties, such as the manipulation of electromagnetic waves through the arrangement of small discrete structures. However, complex designs of mechanically or electrically patterned structures are required to modify these properties. We report on the use of rare earth orthoferrites to tune transmitted waves by engineering the thickness, composition, and temperature using terahertz (THz) time-domain spectroscopy. The modeling of the process of manipulating the transmitted waves helps to elucidate the manipulated amplitude, transmittance, peak height, and frequency. The effectiveness of thickness engineering in tuning the transmitted waves, which conformed to the Beer-Lambert law, was demonstrated. The transmitted waves were also strongly affected by doping. In addition, a thermal anisotropic energy manipulation approach to tuning transmitted waves was developed by lowering the temperature. Rare earth orthoferrites are a kind of effective medium in the THz range and exhibit the signature of natural metamaterials.