Enhanced giant magnetoimpedance in heterogeneous nanobrush

Abstract

A highly sensitive and large working range giant magnetoimpedance (GMI) effect is found in the novel nanostructure: nanobrush. The nanostructure is composed of a soft magnetic nanofilm and a nanowire array, respectively fabricated by RF magnetron sputtering and electrochemical deposition. The optimal GMI ratio of nanobrush is promoted to more than 250%, higher than the pure FeNi film and some sandwich structures at low frequency. The design of this structure is based on the vortex distribution of magnetic moments in thin film, and it can be induced by the exchange coupling effect between the interfaces of nanobrush.

Interface coupling-induced enhancement of magnetoimpedance effect in heterogeneous nanobrush by adjusting textures of Co nanowires

“…The (100)-textured nanobrush shows a better MI ratio, which reaches up to more than 300%. The result is better than our former work [ 24 ]. The MI ratio of the mixed textured ((100), (101), and (002)) nanobrush is about 200%.…”

“…As we know, the magnetocrystalline anisotropy constant K 1 of bulk hexagonal close-packed (hcp) cobalt is 5 × 10 6 erg/cm 3 at room temperature, which is the largest value among the d-band ferromagnetic metals such as Fe, Co, and Ni, and it nearly balances the shape anisotropy ( K s = 6 × 10 6 erg/cm 3 ) of magnetic nanowire [ 26 ]. Thus, purposefully controlling the crystal texture of cobalt nanowires is considered to be valuable for investigating the MI properties at the film part of the nanobrush due to the exchange coupling effect at the interface [ 24 ]. Figure 3 shows XRD patterns of the cobalt nanowire arrays with different textures, and the inset shows the schematic diagrams of the competition between the shape anisotropy and the magnetocrystalline anisotropy.…”

“…Considering the exchange coupling effect, the MI curves in the nanobrush appear to be different from the traditional materials. The MI ratio will not drop dramatically until the external applied field is up to the saturation field [ 24 ]. The (100) texture contributes to the magnetic moments of the interface to distribute on the film; on the contrary, the appearance of the (002) texture may assist the moment to be perpendicular to the film.…”

“…The structure of heterogeneous nanobrush with strong interface coupling may provide new ideas for these challenges. As our former works turn out, the giant MI (GMI) ratio has been enlarged than the single FeNi film on an anodized aluminum oxide (AAO) template, and the exchange coupling effect between nanowires and film has been supposed to be the main reason of the enhanced MI ratio [ 24 ]. However, how the exchange coupling effect acting on MI results is unclear.…”

Enhanced magnetoimpedance effect of carbon fiber/Fe-based alloy coaxial composite by tensile stress

“…The GMI ratio finds maximum at zero field and then gradually decreases and will find the minimum value at higher field. It could be explained by the magnetization rotation model [30,31]. The GMI curves are typical single peak structure, as we know, it means that the magnetic moments trend to distribute along the axis of the fiber.…”