Room‐Temperature Macroscopic Ferromagnetism in Multilayered Graphene Oxide

Abstract Graphene has a long spin lifetime and hyperfine interactions, favoring its potential application as spintronics. Despite the recent discoveries of spin‐containing graphene materials, graphene‐based materials with room‐temperature macroscopic ferromagnetism are extremely rare. In this article, room‐temperature ferromagnetic amorphous graphene oxide (GO) is synthesized by introducing abundant oxygen‐containing functional groups and C defects into single‐layered graphene, followed by a self‐assembly process under supercritical CO2 (SC CO2). Such amorphous GO exhibits the highest saturation magnetization (1.71 emu g−1) and remanent magnetization (0.251 emu g−1) compared to the rest of metal‐free graphene‐based materials at room temperature. Experimental and theoretical investigations attribute such strong ferromagnetism to the bridging of the adjacent graphene layers though the out‐of‐plane oxygen‐containing groups, which leads to asymmetric lattices with large net magnetic moments.