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.