Responsive left-handed behaviour of ferromagnetic microwire composites by in-situ electric and magnetic fields

Abstract Ferromagnetic microwires are feasible building blocks to construct electromagnetic composites with tunable left-handed response towards external stimulus. In this work, a typical left-handed signature of the transmission window was revealed in Co-rich microwires ranging from 9.3 to 10.4 GHz, which arised from the ferromagnetic resonance under a constant DC magnetic field of 8 Oe. Such window was modulated by applying a DC current which tended to compensate the magnetic anisotropy of the microwires. Currents of up to 100 mA were applied to the wire resulting in a maximum transmission bandwidth at 60 mA. Such effect was corroborated by the competition between magnetic domains restoration and Joule effect in the presence of DC current. Embedding the microwire into fibre-reinforced 913 E-glass prepregs realised a metacomposite with a corresponding window in 8.5–10.2 GHz benefited by the restoration of circumferential domain structures during the composite curing process. Further, it was observed a dependence of electromagnetic behaviour on the angle between the microwire and the reinforcing glass fibers of the matrix. This investigation provides essential guidance for designing and tuning frequency-selective wave transmitting structures for sensing and cloaking applications.