Meissner effect in nonstandard superconductors

TL;DR

This paper investigates the Meissner effect in superhydrides, particularly sulfur hydride, revealing that the magnetic expulsion pressure is significantly larger than in standard superconductors, indicating a potentially different superconducting nature.

Contribution

It highlights that superhydrides exhibit a much larger Meissner pressure, suggesting they may be qualitatively different from conventional superconductors.

Findings

Meissner effect observed in sulfur hydride

Meissner pressure is much larger than in standard superconductors

Implication that superhydrides might be fundamentally different

Abstract

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.