High-temperature superconductivity in La4H23 below 100 GPa

High-temperature superconductivity has been observed in binary hydrides such as LaH10 at pressures close to 180G Pa, whereby hydrogen cagelike structures have been identified as a common motif beneficial for high critical temperatures Tc. Efforts are now focused on finding hydride high-temperature superconductors at lower pressures. We present evidence for high-temperature superconductivity in binary La4 H23 at a pressure of P=95 G Pa, 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 Tc∼0K. 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.