Analyses on double resonance behavior in microwave magnetic permeability of multiwalled carbon nanotube composites containing Ni catalyst

The double resonance behavior of microwave magnetic permeability has been observed for multiwalled carbon nanotube composites containing Ni catalyst. One of them is due to the natural resonance at 6.00 GHz and another is due to the exchange resonance at 10.11 GHz. The natural resonance is dependent on magnetocrystalline anisotropy and shape anisotropy of Ni nanostick catalyst and the calculated result of exchange resonance mode with a few modifications was close to the experiment. It is believed that the coexistence of natural resonance and exchange resonance is benefial to large bandwidth as a microwave absorber. (c) 2008 American Institute of Physics.