Measuring the Meissner effect at megabar pressures

Since 2014, when the research group of Professor Tian Cui ( Jilin University) predicted [1] (and experiments [2] confirmed) the existence of an unusual highpressure compound, H3S, with superconductivity at 191–204 K, a new era in studies of superconductivity began. In 2019, a new record of high-temperature superconductivity was set, with LaH10 experimentally proven to be a superconductor with a nearly room-Tc of 250– 260 K [3,4]. H3S and LaH10 cannot be used in practical applications, because they exist only at megabar pressures, but their study may hint at which compounds can be room-temperature superconductors at normal pressure. The unusually high electron–phonon coupling constants (λ > 2) of these materials also make them interesting from the physical point of view. The first test of superconductivity under pressure is the measurement of electrical resistivity and of the isotope effect. However, magnetic measurements are also highly desirable. From the technical point of view, such experiments are