Magnetism and Superconductivity in Hydrogenated Graphite Foils

We have previously found magnetism and superconductivity in hydrogenated graphite [Gheorghiu, et al. (2020)]. Herein, the two phenomena are observed in hydrogenated graphite foils. As the strength of the magnetic field is increased, the temperature-dependent magnetization shows several transitions between different states: from Néel paramagnetic, to antiferromagnetic, to ferromagnetic superconductor, to high-temperature superconductor with the critical temperature for the dominant phase Tc ∼ 50–60 K. The latter might be an orbital paramagnetic glass ordering of π Josephson-coupled SC domains akin to a macroscopic quantization of the system. The magnetization loops show the kink feature characteristic to granular SC. The ferromagnetism is observed up to room temperature. Thus, we observe both magnetism and superconductivity in hydrogenated graphite foils.