Magnetic Tuning of Metasurfaces Using Ultrathin Flexible Metals Bonded With Ferrite Patches

Active control of metasurfaces can be achieved using the magnetic effect, which is, however, quite weak. Here, a different method for realizing the magnetic tuning is proposed. For this purpose, a simple two-dimensional array of split-ring resonators (SRRs), consisting of ultrathin flexible metals bonded with Mn-Zn ferrite patches, has been designed. With the external magnetic field, a magnetic force will be exerted on the ferrite patches, leading to the deformation of the meta-atoms (i.e., the flexible SRRs). Consequently, the gap size of the SRRs can be altered continuously by varying the magnetic field, which modifies the electromagnetic properties of the metasurface. The active tuning of resonance frequency and transmission efficiency has been demonstrated with theory and experiments in the microwave band. The result may be useful for constructing magnetically- controllable switches and modulators as well as the magnetic sensors operating in the microwave or THz regime.