Magnetic field screening in hydrogen-rich high-temperature superconductors

In the last few years, the superconducting transition temperature, T-c, of hydrogen-rich compounds has increased dramatically, and is now approaching room temperature. However, the pressures at which these materials are stable exceed one million atmospheres and limit the number of available experimental studies. Superconductivity in hydrides has been primarily explored by electrical transport measurements, whereas magnetic properties, one of the most important characteristic of a superconductor, have not been satisfactory defined. Here, we develop SQUID magnetometry under extreme high-pressure conditions and report characteristic superconducting parameters for Im-3m-H3S and Fm-3m-LaH10-the representative members of two families of high-temperature superconducting hydrides. We determine a lower critical field H-c1 of similar to 0.82 T and similar to 0.55 T, and a London penetration depth lambda(L) of similar to 20 nm and similar to 30 nm in H3S and LaH10, respectively. The small values of lambda(L) indicate a high superfluid density in both hydrides. These compounds have the values of the Ginzburg-Landau parameter kappa similar to 12-20 and belong to the group of moderate type II superconductors, rather than being hard superconductors as would be intuitively expected from their high T(c)s. Superconductivity in hydrides has been primarily explored by electrical transport measurements. Here, the authors perform SQUID magnetometry under extreme high-pressure and report characteristic superconducting parameters for Im-3m-H3S and Fm-3m- LaH10-the representative members of two families of high-temperature superconducting hydrides.

Automated summary

In recent years, the transition temperature Tc of hydrogen-rich compounds has significantly increased and is now close to room temperature. However, the high pressures required for stability of these materials limit experimental studies. While superconductivity in hydrides has mainly been explored through electrical transport measurements, the magnetic properties, an important characteristic of superconductors, have not been well defined. In this study, the authors developed SQUID magnetometry under extreme high-pressure conditions to investigate the superconducting parameters of Im-3m-H3S and Fm-3m-LaH10, two representative families of high-temperature superconducting hydrides.