Ternary Superhydrides Under Pressure of Anderson's Theorem: Near‐Record Superconductivity in (La, Sc)H₁₂

Lanthanum‐hydrogen system and its derivatives hold significant promise for achieving room‐temperature superconductivity. In this study, the formation of ternary lanthanum‐scandium superhydrides is examined at pressures up to 220 GPa. The primary product of the LaSc alloy's reaction with hydrogen is a newly discovered cubic (La,Sc)H 12 , demonstrating a clear superconducting transition in all six channels of the van der Pauw‐contact scheme at 244–248 K. In this compound with an unusually large unit‐cell volume, virtually no magnetoresistance is observed in fields up to 68 Tesla. Synthesized samples of (La,Sc)H 12 demonstrate pronounced superconducting diode and SQUID‐like effects at a record high temperature of 233 K, which opens up prospects for the use of superhydrides in compact electronics. Furthermore, the analysis reveals the possible formation of a lower hexagonal polyhydride (La,Sc)H 6‐7 , which can potentially account for the drop in electrical resistance observed near 274 K. This anomaly between 265–290 K also appears in the radio‐frequency transmission measurements and may be of a superconducting nature.