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 similar to 70 K in a SnHx sample synthesized by laser heating Sn and ammonia borane inside a diamond anvil cell at similar to 200 GPa. The main phase of the obtained sample can be indexed with the monoclinic C2/m SnH12 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 SnHx with an upper critical field mu H-0(c)2(0) approximate to 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. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The possible occurrence of superconducting transition in a SnHx sample synthesized under high pressure conditions by laser heating is reported, with an upper critical temperature of about 70 K. This finding provides a new direction for the development of high-temperature superconductors using metallic alloys.