Giant enhancement of superconducting critical temperature in substitutional alloy (La,Ce)H9
Jingkai Bi, Yuki Nakamoto, Peiyu Zhang, Katsuya Shimizu, Bo Zou, Hanyu Liu, Mi Zhou, Guangtao Liu, Hongbo Wang, Yanming Ma
Abstract
Abstract A sharp focus of current research on superconducting superhydrides is to raise their critical temperature T c at moderate pressures. Here, we report a discovery of giant enhancement of T c in CeH 9 obtained via random substitution of half Ce by La, leading to equal-atomic (La,Ce)H 9 alloy stabilized by maximum configurational entropy, containing the LaH 9 unit that is unstable in pure compound form. The synthesized (La,Ce)H 9 alloy exhibits T c of 148–178 K in the pressure range of 97–172 GPa, representing up to 80% enhancement of T c compared to pure CeH 9 and showcasing the highest T c at sub-megabar pressure among the known superhydrides. This work demonstrates substitutional alloying as a highly effective enabling tool for substantially enhancing T c via atypical compositional modulation inside suitably selected host crystal. This optimal substitutional alloying approach opens a promising avenue for synthesis of high-entropy multinary superhydrides that may exhibit further increased T c at even lower pressures.