Mid-infrared tunable magnetic response in graphene-based diabolo nanoantennas

The combination of metallic structure and graphene has become a promising platform for electrically controlled plasmonic devices. However, the current designs mainly utilize graphene as an active medium, which only modulate the devices performance slightly and the applications in tunable magnetic response have not been explored. Here, we explore the applications of graphene in the control of magnetic resonance in nanoantennas. By optimizing the design and parameter of the nanoantennas, gold-graphene hybrid diabolo antennas turn out to be the best candidate to achieve tunable magnetic response in mid-infrared wavelength range. The magnetic resonance of gold-graphene hybrid diabolo antennas has been significantly tuned from 32.3 μm to 19.8 μm, which is beyond one order of magnitude higher than conventional diabolo nanoantennas with graphene as active materials below the antenna structure. The corresponding absorption modulation and magnetic field enhancement can be as high as 12% and 1460%, respectively.