Orientated hydrogen chains favor superconductivity in germanium sulfur hydrides

Abstract

Hydrogen-rich compounds, as the closest to room-temperature superconductors discovered in recent years, have attracted the research interest of scientists. Especially, the recent theory-orientated discovery of record high-temperature superconductivity (T_c ∼ 330 K) in clathrate CeH₁₈ is an important advancement toward room-temperature superconductors. In this work, we systematically investigated the phase diagram, stability, and superconducting properties of GeSH_x compounds (x = 7, 8, 10, 12, 14 and 16) under compression. Here we report a superconductive structure of GeSH₁₄ with the P2₁/m space group, possessing a predicted critical temperature T_c of 128 K at 180 GPa. Strikingly, P2₁/m GeSH₁₄ is composed of orientated hydrogen chains bridging the adjacent Ge–S–H polyhedron layers, and is distinctly different from the typical clathrate structure in most high-T_c hydrides. Moreover, the hydrogen components mainly exist in the form of covalent atomic chains, which is crucial for stabilizing the hydrogen-rich compound and is favorable for superconductivity. The role of hydrogen atomic chains in the superconductivity is investigated extensively, and the superconducting mechanism of high-T_c is further explored. This work provides a new way of searching for high-temperature hydrogen-rich superconductors.