High-temperature superconductivity in La4H23 below 100 GPa

High-temperature superconductivity has been observed in binary hydrides such as {LaH}₁₀ at pressures close to 180 GPa, whereby hydrogen cagelike structures have been identified as a common motif beneficial for high critical temperatures {T}_c. Efforts are now focused on finding hydride high-temperature superconductors at lower pressures. We present evidence for high-temperature superconductivity in binary {La}₄{H}₂₃ at a pressure of P=95 GPa, with A15-type arrangement of the lanthanum atoms in the type-I clathrate structure. We synthesize {La}₄{H}₂₃ from a lanthanum film capped with a palladium catalyst promoting the dissociation of hydrogen. In resistance measurements, we observe superconductivity with a transition temperature {T}_c∼90 K. The A15-type lanthanum sublattice is identified in x-ray diffraction on the same sample, in agreement with previous x-ray diffraction and structure prediction studies. Our study reinforces the favorability of cagelike networks of the hydrogen lattice for high-temperature superconductivity. Published by the American Physical Society 2024