Investigation on Record Ambient-Pressure Superconductivity via Pressure Quenching

The search for superconductors with a higher transition temperature (T_c) has been one of the major driving forces in the long-sustained research effort on superconductivity ever since its discovery in 1911. However, since 1993 significant advancements in T_c have been achieved only under high pressures, e.g. 164 K in Hg1223 under 31 GPa and above 200 K in hydrides under pressure above 150 GPa, preventing the realization of superconductivity’s full potential. To address this challenge, stabilizing high-pressure-induced/-enhanced high-T_c phases at ambient pressure is essential. Recently, we developed a pressure-quench protocol (PQP) to stabilize pressure-induced/-enhanced superconducting states at ambient pressure and subsequently achieved a record ambient-pressure T_c  above 150 K in Hg1223 via PQP. This breakthrough opens new avenues for stabilizing and exploring ambient-pressure high-T_c superconducting states that were previously only accessible under pressure, paving the way for deeper understanding and practical applications of high-T_c superconductivity. Studies on the dynamics of pressure-quenching via different probes, including synchrotron X-ray diffraction and nitrogen-vacancy (NV) center quantum sensing, will also be discussed. The impact of our work extends beyond superconductivity research, as PQP offers an effective means to retain at ambient pressure quantum metastable states that possess favorable or unique properties initially existing only under high pressure.