High-Temperature Superconductivity in H3S up to 253 K at a Pressure of 140 GPa by Doping Holes

To understand the superconductivity and explore the improvement of transition temperature of H3S, we investigate the effect of electron or hole injection in H3S with the Im (3) over barm phase. The results show that the increase of electron-phonon coupling constant mainly comes from the softening of phonons when electrons are introduced, while the electron-phonon coupling strength mainly depends on the change of the electronic density of states at Fermi level when holes are introduced. We find that the introduction of holes can improve the transition temperature, and the increase of hole concentration can further reduce the lowest pressure point satisfying the stability. In the range of 0.3-0.5 hole per unit cell, the transition temperature of the charged H3S can be improved to 253 K, which is about 25% larger than the neutral case (204 K at 200 GPa), and the lowest pressure point satisfying the stability is reduced to 140 GPa. Combining the hole doping with the pressure effect, we reveal that the enhancement of transition temperature is driven by the increase of electronic states at Fermi level and the softening of phonons. As a result, a novel way is suggested to further optimize the transition temperature of hydrogen-rich materials.