Lower pressure phases and metastable states of superconducting photo-induced carbonaceous sulfur hydride

Abstract

Room-temperature superconductivity was recently discovered in carbonaceous sulfur hydride (C-S-H) close to 3 Mbar. We report significant differences in the superconducting response of C-S-H, with a maximum TC of 191(1) K, below a 1 Mbar. Variations in intensity of the C-H Raman modes reveal carbon content can vary between crystals synthesized with the same photo-induced method. Synchrotron single crystal x-ray diffraction identifies polymorphism with increasing degrees of covalency. These unique metastable states are highly sensitive to thermodynamic pathways.

Superconducting Materials: Judge, Jury and Executioner of BCS-electron-phonon Theory

“…Ref. [199] reports a variety of different T c s in C-S-H for crystals synthesized in the same way explaining that they are "highly sensitive to thermodynamic pathways". In addition, because of the way samples are prepared, with laser heating with a focused beam of diameter much smaller than the size of the sample that the beam is scanning through, the resulting compounds are expected to be highly inhomogeneous and granular in nature.…”