Multiple micro wave absorption in ferromagnetic wire and box arrays

Unique microwave absorption was observed in a new type of artificially structured material consisting of ferromagnetic Ni80Fe20 wire and box arrays prepared by high-resolution electron-beam lithography and lift-off techniques. When a magnetic field was applied parallel and normal to the array plane, multiple absorption was regularly observed at higher and lower fields, respectively, than the main absorption associated with a uniform precessional mode (ferromagnetic resonance). Magnetic dipolar standing waves excited in the arrays are probably correlated with this phenomenon.