Superior magnetoresistance performance of hybrid graphene foam/metal sulfide nanocrystal devices

Interfaces between metals and semiconducting materials can inevitably influence the magnetotransport properties, which are crucial for technological applications ranging from magnetic sensing to storage devices. By taking advantage of this, a metallic graphene foam is integrated with semiconducting copper-based metal sulfide nanocrystals, i.e., Cu₂ZnSnS₄ (copper-zinc-tin-sulfur) without direct chemical bonding and structural damage, which creates numerous nanoboundaries that can be basically used to tune the magnetotransport properties. Herein, the magnetoresistance of a graphene foam is enhanced from nearly 90 to 130% at room temperature and under the application of 5 T magnetic field strength due to the addition of Cu₂ZnSnS₄ nanocrystals in high densities. We believe that the enhancement of magnetoresistance in hybrid graphene foam/Cu₂ZnSnS₄ nanocrystals is due to the evolution of the mobility fluctuation mechanism, triggered by the formation of nanoboundaries. Incorporating Cu₂ZnSnS₄ nanocrystals into a graphene foam not only provides an effective way to further enhance the magnitude of magnetoresistance but also opens a suitable window to achieve efficient and highly functional magnetic sensors with a large, linear, and controllable response.