Magnetism and Superconductivity in Hydrogenated Graphite Foils

Abstract

Unique to certain unconventional superconductors is the coexistence of magnetism and superconductivity. We have previously found ferromagnetism and superconductivity in hydrogenated graphitic materials. Herein we present similar as well as completely new findings this time applicable to hydrogenated graphite foils. As the strength of the magnetic field is increased, the temperature-dependent magnetization shows several important transitions. From a Neel paramagnetic-antiferromagnetic transition, to a ferromagnetic superconductor state, to an orbital paramagnetic glass high-temperature superconductor with critical temperature for the dominant phase at Tc = 50 to 60 K. The ferromagnetic state is observed up to room temperature. Thus, the magnetism of hydrogenated low-density carbon graphite foils plays an important role in establishing electronic correlations of which some are superconducting in nature.