Superconductivity up to 243 K in the yttrium-hydrogen system under high pressure

The discovery of high temperature superconductivity in hydrogen-rich compounds stimulates further extensive studies. Here, the authors report superconductivity in pressurized yttrium-hydrogen system with highest predicted T-c among binary compounds. The discovery of superconducting H3S with a critical temperature T-c similar to 200 K opened a door to room temperature superconductivity and stimulated further extensive studies of hydrogen-rich compounds stabilized by high pressure. Here, we report a comprehensive study of the yttrium-hydrogen system with the highest predicted T(c)s among binary compounds and discuss the contradictions between different theoretical calculations and experimental data. We synthesized yttrium hydrides with the compositions of YH3, YH4, YH6 and YH9 in a diamond anvil cell and studied their crystal structures, electrical and magnetic transport properties, and isotopic effects. We found superconductivity in the Im-3m YH6 and P6(3)/mmc YH9 phases with maximal T(c)s of similar to 220 K at 183 GPa and similar to 243 K at 201 GPa, respectively. Fm-3m YH10 with the highest predicted T-c > 300 K was not observed in our experiments, and instead, YH9 was found to be the hydrogen-richest yttrium hydride in the studied pressure and temperature range up to record 410 GPa and 2250 K.

Automated summary

Researchers studied the superconductivity of the yttrium-hydrogen system under pressure conditions and discovered new high-temperature superconducting phases. They synthesized yttrium hydrides with different compositions and detected superconductivity with relatively high critical temperatures.