Hydrogen-dominated materials under high pressure: clue and route to room temperature superconductors

Metallic hydrogen under high pressure is believed to be a room-temperature superconductor. However, there are no experimental evidence for the predicted metallic state. As an alternative, hydrogen-dominated materials can metallize at lower pressures because of chemical pre-compressions, which are potential high temperature superconductors. Therefore, hydrogen-dominated materials are expected to become a new member of superconductor family: hydrogen-based superconductor.
Here, we theoretically predicted H₃S with Im-3m symmetry to be a high-temperature superconductor with T_c reaching as high as 200 K at high pressure and proposed that H₃S can be formed at high pressure by two main ways: 3H₂S→2H₃S+S, 2H₂S+H₂→2H₃S ^[1]. Then, these results have been confirmed by several in situ high pressure experiments^[2-4]. Furthermore, we also explored high temperature superconductivity in other hydrogen-dominated materials at high pressures, including ternary hydrides.
[1] D. Duan, T. Cui, et al. Sci. Rep., 4, 6968 (2014); D. Duan, T. Cui, et al. Phys. Rev. B, 91, 180502 (2015).
[2] A. P. Drozdov, M. I. Eremets, et al. Nature, 252, 73-76 (2015).
[3] M. Einaga, K. Shimizu, et al. Nature Phys., 12, 835-838 (2016).
[4]X. Huang, T. Cui, et al. arXiv:1610.02630 (2016).