Hydride superconductors (e.g., LaH10, CeH9, ThH10, YH6) frequently exhibit upper critical fields Hc2(0) that can exceed the ~20 T ceiling of conventional DC superconducting magnets. Reliable experimental determination of Hc2(T) in these compounds therefore requires access to pulsed magnetic fields. But coupling pulsed magnets to diamond anvil cells (DACs) is far from trivial: conductive cell bodies and gaskets can screen the field, induced eddy currents generate significant heating, and the DAC’s geometry limits bore diameter of magnets.
I will report results from a multi-year pulsed-magnetic-field campaign on superconducting metal superhydrides, carried out primarily at the Dresden High Magnetic Field Laboratory (HLD, 150 ms pulse, up to 68–70 T) and the Steady High Magnetic Field Facility in Hefei (DC, up to 35–45 T), together with a subsequent engineering study aimed at extending these measurements toward 100 T performed at the MegaGauss laboratory. Using NiCrAl DACs with NiCr-wire heaters, we measured the upper critical field Hc2(T) for a broad family of hydride superconductors —YH6, CeH9, CeH10, ThH9, SnH4, (La,Nd)H10, (La,Sc)H10-12 and (Ca,Nd,Zr)H9+x. Most of superhydrides show an anomalous linear Hc2(T) ∝ (T–Tc), attributed to their highly disordered lattice. Magnetoresistance of superhydrides is typically linear and takes a slight positive or almost zero values. For several hydrides (La4H23 and CeH9-10) we observed a pronounced negative magnetoresistance and non-Fermi-liquid (“strange metal”) behavior, reproduced independently at Dresden and Hefei high-magnetic field laboratories.