High-Pressure Magnetic Susceptibility Studies on Carbonaceous Sulfur Hydride

The most significant discovery in reaching high-temperature superconductivity is the pressure-driven disproportionation of hydrogen sulfide (H₂S) to H₃S. As H₂S readily mixes with hydrogen to form guest-host structures at lower pressures, we consider the comparable size of methane (CH₄) to H₂S should allow molecular exchange within a large assemblage of van der Waals solids that are (highly) hydrogen-rich with H₂ inclusions that are then the building blocks for novel superconducting compounds at extreme conditions. A superior test for superconductivity is the search for a strong diamagnetic transition in the magnetic susceptibility. Here, we report superconductivity in a photochemically transformed carbonaceous sulfur hydride system using a novel double-frequency modulation method with a transition temperature as high as 262 K. Double-frequency method displayed significant improvements over the standard susceptibility technique, allowing the detection of the superconducting transition for very small samples such as Carbonaceous Sulfur Hydride