Retention of high-pressure-induced superconducting and non-superconducting phases in high-temperature superconductors at ambient*

The search for high-temperature superconductivity (HTS) in hydrogen and hydrogen-rich compounds under high pressure has a long history. Recently, several reports (1-4) of high T_c up to 288 K in hydrides under pressure of up to 267 GPa have appeared. The ultrahigh pressure needed to create the HTS in hydrides has hampered the detailed study of the phenomenon, as well as any applications. To lower the required pressure, even to zero, we have developed a pressure-quench process (PQP) and have demonstrated it successfully in stabilizing at ambient the high-pressure-induced HTS phase and other phases in FeSe and Cu-doped FeSe (5). It is not inconceivable that the PQP may be adapted for hydrides with T_c approaching room temperature. The results will be presented, and both the opportunities and challenges will be discussed.

References: [1] A. P. Drozdov et al., Nature 525, 73 (2015); [2] M. Somayazulu et al., PRL 122, 027001 (2019); [3] E. Snyder et al., Nature 586, 373 (2020); [4] D. V. Semenok et al., Materials Today 33, 36 (2020); [5] L. Z. Deng et al., PNAS USA 118, e2108938118 (2021)