  In this work, we report the design of a wavelength-tunable infrared
metamaterial by exciting magnetic resonance with phase transition of vanadium
dioxide (VO2). Numerical simulation shows a broad absorption peak at the
wavelength of 10.9 um when VO2 is a metal, but it shifts to 15.1 um when VO2
changes to dielectric phase below its phase transition temperature of 68degC.
The large tunability of 38.5% in the resonance wavelength stems from the
different excitation conditions of magnetic resonance assisted by plasmon in
metallic VO2 but optical phonons in dielectric VO2. The physical mechanism is
elucidated with the aid of electromagnetic field distribution at the resonance
wavelengths. A hybrid magnetic resonance mode due to plasmon-phonon coupling is
also discussed. The results here would be beneficial for active control in
novel electronic, optical and thermal devices.
