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Graphene (Gr), a well-known 2D material, has been under intensive investigation in the last decade due to its high potential applications in industry and advanced technological elements. The Gr, while composed with magnetic materials, has opened new opportunities for further developments of magnetic based devices.Here, we report a mass production of Gr/Ni composite powders using electrochemical exfoliation/deposition method with different magnetic strengths of the final composite material. We applied the magnetic composite materials in a magnetoimpedance (MI) based sensor and observed significant enhancement in the MI effect and its field sensitivity. Such magnetic composites with controlled magnetization strengths are coated on the MI-ribbon sensor surface and different MI responses are observed. The MI response of a ribbon coated with a Gr/Ni layer is theoretically determined based on an electrodynamic model with a qualitative consistency between the experimental results and the theoretical model. Our comprehensive study can be applied in high performance functionalized MI based magnetic sensors and devices.

Proximity-induced magnetism (PIM) in graphene (Gr) adjacent to magnetic specimen has raised great fundamental interests. The subject is under debate and yet no application is proposed and granted. In this paper, toward accomplishment of fundamental facts, we first explore the effect of particle size and clustering in the PIM in Gr nanoplates (GNPs)/yttrium iron garnet (YIG) magnetic nanoparticle (MNP) composite. Microscopic analyzes suggest that fine MNPs distributed uniformly on the GNPs have higher saturation magnetization due to the PIM in Gr. We propose that such magnetic plates can thus be used to shield the stray field generated on the surface of magnetic sensors and play a role as a magnetic lens to prevent the field emanating outside the body of magnetic specimen. The GNPs/YIG composites are coated on a magnetic ribbon and proposed for application in magneto-impedance (MI) sensors. We show that such planar magnetic flakes enhance the MI response against the external applied magnetic field significantly. The suggested application can be furthermore developed toward bio-sensing and magnetic shielding in different magnetic sensors and devices.

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