Physics news on the Internet: May 2024

Room-temperature superconductivity discovered recently in hydrides only exists under a giant pressure of 267 GPa. In this connection, the search for the possibility of lowering pressure while retaining superconductivity has become a topical problem. L Deng (University of Houston, USA) and coauthors have carried out an experiment showing, based on the example of another type superconductorÐ iron selenide (FeSe) single crystalsÐ that the problem can be solved through pressure-induced quenching, i.e., an abrupt pressure removal at low temperature [1]. The superconducting transition temperature of FeSe is Tc 9 K at atmospheric pressure and Tc ˆ 37 K at a pressure of several GPa. FeSe specimens were pressed in a diamond anvil to 4.15 GPa and cooled to 4.2 K, and then the pressure was abruptly removed. After such a quenching, the specimens retained Tc ˆ 37 K at atmospheric pressure for 7 days. The transition between orthorhombic and tetragonal structures of the crystal lattice, when FeSe remains in the metastable phase after quenching, is likely to explain the quenching effect on Tc. The results obtained for FeSe hold promise that pressure-induced quenching may also stabilize hydride superconductors. For high-temperature superconductors, see [2]. The 2003 Nobel Prize laureate in physics V L Ginzburg placed the creation of room-temperature superconductors on the list of the most topical problems in physics [3].