Ferromagnetic correlation in hydrogen doped highly oriented pyrolytic graphite

Observation of granular superconductivity in water doped graphite materials has motivated recent research because of the unexplored scenarios in the field of magnetism and spintronics. Diffusion of hydrogen and/or oxygen species has been reported to promote doping within graphitic grains; however, the origin and dynamics of the magnetic phenomena (i.e. superconductive ordering), which arise as a consequence of this doping-process, are still not well understood. In this work, we investigated the relationship between magnetic-ordering and hydrogen/oxygen doping in highly oriented pyrolytic graphite (HOPG). Diamagnetic lamellae exfoliated from HOPG were soaked in water and alcoholic beverages, with a variable ethanol concentration (0–60%). Superconducting quantum interference device (SQUID), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were employed for an in-depth characterization of undoped and doped lamellae. Presence of a hydrogen-induced ferromagnetic ordering in the π-electrons is demonstrated. To further enhance infiltration and achieve enhanced ferromagnetic signals, Isostatic-Pressure-Wine-Doping was employed. The application of pressure-induced disruption of the regular mosaic distribution within HOPG layers enhanced 1) the diffusion of the dopant within the layers and 2) the ferromagnetic response of the samples.