Meissner effect in nonstandard superconductors

• DOI: 10.1016/j.physc.2021.1353896
• Publication Date: 2021-05-31T15:57:04Z
• Authors: J.E. Hirsch; F. Marsiglio
• Keywords: Superconductivity (cond-mat.supr-con); Condensed Matter - Superconductivity; 0103 physical sciences; FOS: Physical sciences; 01 natural sciences; 7. Clean energy

It was recently pointed out that so-called "superhydrides", hydrogen-rich materials that appear to become superconducting at high temperatures and pressures, exhibit physical properties that are different from both conventional and unconventional standard type I and type II superconductors [1,2]. Here we consider magnetic field expulsion in the first material in this class discovered in 2015, sulfur hydride [3]. A nuclear resonant scattering experiment has been interpreted as demonstration that the Meissner effect takes place in this material [4,5]. Here we point out that the observed effect, under the assumption that the system is in thermodynamic equilibrium, implies a Meissner pressure [6] in this material that is {\it much larger} than that of standard superconductors. This suggests that hydride superconductors are qualitatively different from the known standard superconductors {\it if} they are superconductors.<br/>6 pages, 2 figures<br/>