Press Releases
Oct. 25, 2007

A Millimeter Wave Absorber Based on Gallium Substituted ε-Iron Oxide Nanomagnets

Millimeter waves are beginning to be used in electronic devices for high-speed wireless communication. However, materials that effectively restrain electromagnetic interference (EMI) in the region of millimeter waves almost do not exist. This time Prof. Shin-ichi Ohkoshi (Department of Chemistry, School of Science, The University of Tokyo) et al., developed a new EM absorber composed of ε-Fe2O3 (0.10 ≤ x ≤ 0.67) nanomagnets, which shows a ferromagnetic resonance in the region of 35-147GHz. In addition, the possibility that the resonance frequency can achieve 200GHz at x→0 is also suggested. The millimeter wave absorber of fr > 80GHz based on a magnetic material has not been reported to date. The present developed materials are suitable for an absorber to restrain the EMI (for example, a millimeter wave absorber painted on the wall of office, private and medical room, or the body of car, train, and airplane), and an optoelectronic device to stabilize the EM sending (for example, a circulator and an isolator for millimeter waves of needless magnetic field). Furthermore, because our materials are composed of a metal oxide, it is stable over long periods, and such millimeter wave absorbers are advantageous for industrial applications.

The paper of this work is selected to be highlighted at the inside cover on Angewandte Chemie International Edition.