Novel Synthesis Route and Observation of Superconductivity in the Se-H System at Extreme Conditions

The recent observation of highest Tc ~ 203 K in the S-H system at high pressure by Drozdov et al. have inspired several theoretical studies for superhydrides with higher predicted Tc values. However there is scarcity of experimental observation of Tc in synthesized higher hydrides so far. We have chosen a novel route to synthesize higher hydride of Se, the closest analog of sulfur, using solid media and laser heating at pressure close to ~ 10 GPa. The synthesis of hydrogen rich van der Waals compound (H₂Se)₂H₂ is confirmed using in-situ Raman spectroscopy. The synthesized compound shows metallic behavior on compression and superconducting transition temperature ~ 105 K has been observed using four probe technique at ~135 GPa.