Future Study of Dense Superconducting Hydrides at High Pressure

Abstract

The discovery of a record high superconducting transition temperature (Tc) of 288 K in a pressurized hydride inspires new hope to realize ambient-condition superconductivity. Here, we give a perspective on the theoretical and experimental studies of hydride superconductivity. Predictions based on the BCS–Eliashberg–Midgal theory with the aid of density functional theory have been playing a leading role in the research and guiding the experimental realizations. To date, about twenty hydrides experiments have been reported to exhibit high-Tc superconductivity and their Tc agree well with the predicted values. However, there are still some controversies existing between the predictions and experiments, such as no significant transition temperature broadening observed in the magnetic field, the experimental electron-phonon coupling beyond the Eliashberg–Midgal limit, and the energy dependence of density of states around the Fermi level. To investigate these controversies and the origin of the highest Tc in hydrides, key experiments are required to determine the structure, bonding, and vibrational properties associated with H atoms in these hydrides.

Granular Superconductivity in Hydrides under Pressure

“…These properties would provide evidence that the materials trap mag-netic flux and hence that persistent currents can flow in hydrides under pressure without dissipation, thus proving that the materials are indeed superconductors, disproving suggestions to the contrary [14,19,22,23,55]. No such hysteretic behavior in transport properties has been reported to date to our knowledge, for any of the more than 15 different hydrides under pressure claimed to be high temperature superconductors, for which extensive transport measurements have been reported [5][6][7][8][9]. We suggest that these experiments should be urgently performed.…”

Granular Superconductivity in Hydrides Under Pressure

“…These proper-ties would provide evidence that the materials trap magnetic flux and hence that persistent currents can flow in hydrides under pressure without dissipation, thus proving that the materials are indeed superconductors, disproving suggestions to the contrary [14,19,22,23,55]. No such hysteretic behavior in transport properties has been reported to date to our knowledge, for any of the more than 15 different hydrides under pressure claimed to be high temperature superconductors, for which extensive transport measurements have been reported [5][6][7][8][9]. We suggest that these experiments should be urgently performed.…”

“…Large drops [1] (and sometimes small drops [2,3]) in resistance are readily interpreted as indicating superconductivity, particularly when it is expected that the material should be a high temperature superconductor due to an earlier theoretical prediction [4]. In that way, more than 15 different hydrides under pressure have been claimed to be high temperature superconductors in recent years [5][6][7][8][9].…”

Research of Theory on High Temperature Superconductivity, Super Fluidity and BEC

“…Errea, et al discussed quantum crystal structure in the 250-kelvin superconducting lanthanum hydride [13]. Wang, et al researched future study of dense superconducting hydrides at high pressure [14]. Hydrogen is the lightest element, and the hydrogen bond is one of the strongest chemical bonds.…”