Possible superconductivity at ∼70 K in tin hydride SnHx under high pressure

Hydrides of air non-sensitive IVA-group elements were predicted to be possible high temperature superconductors (HTS) by N.W. Ashcroft (PRL 92 , 187002 (2004)), which inspired the exploration of hydrogen dominated metallic alloy-based HTS. Although the IVA-group hydrides have been investigated theoretically by several groups, the experimental realization of any superconducting IVA-group hydrides is still lacking. Here, we report on the observation of the possible superconducting transition at ∼70 K in a SnH x sample synthesized by laser heating Sn and ammonia borane inside a diamond anvil cell at ∼200 GPa. The main phase of the obtained sample can be indexed with the monoclinic C 2/ m SnH 12 via comparison with the theoretical structural modes, which have distinct H-network with respect to the clathrate-type structure. A sudden drop of resistance and the systematic downward shift under external magnetic fields signal the occurrence of superconductivity in SnH x with an upper critical field μ 0 H c2 (0) ≈ 11.2 T, and the resistive broadening behavior in magnetic fields follows the trend of traditional standard superconductors. This work provides an alternative way to obtain metal hydrides HTS via p electron-metals rather than the active s or f electron-metals (such as Mg, Ca, La, Y, Ce), which will stimulate the experimental exploration of hydrides HTS in different element groups. A new metal hydride SnH x superconductor with T c ≈ 72 K is synthesized at ∼200 GPa. • A new hydride SnH x is synthesized at ∼200 GPa, and is confirmed to be a high-temperature superconductor (HTS) with T c ≈ 72 K. • The obtained SnH x is a p-electron metal hydride superconductor containing H 2 and H 4 molecule-like units. • SnH x is the first experimentally synthesized HTS among the IVA-group hydrides.