AI 中文总结
本研究通过多类实验与理论计算重新探究YH₆、YH₉、YH₁₀的超导性质，发现二元钇超氢化物无室温超导可能，明确了相关超导参数及非谐效应对YH₁₀超导温度的影响。
AI 中文摘要
钇多氢化物是高压超导领域的基准材料，但Y-H体系的若干关键性质仍未得到充分表征。本研究结合接触式输运、非接触式射频测量、脉冲场实验及第一性原理计算，在140-213 GPa压力范围内重新研究YH₆、YH₉与YH₁₀。钇氢化物YH₆（T_c=218-221 K）和YH₉（T_c=235-237 K）呈现窄超导转变（ΔT_c=2-5 K），接近热涨落所限定的极限。对YH₆开展最高60 T的脉冲场测量，构建了扩展超导相图，其线性斜率dB_{c2}/dT=-0.52 T/K，30 T以上出现明显的转变展宽，且正常态磁阻可忽略不计。本研究报道了YH₆的射频交流磁化率研究，通过非接触几何下的高频场屏蔽为超导性提供了证据。涉及Pd引入、Pd薄膜溅射及Al合金化的实验显示，高温超导被强烈抑制，在78-120 K以上未检测到任何转变。最后，采用含随机自洽谐近似的密度泛函理论、超导密度泛函理论及全带宽Migdal-Eliashberg计算，本研究表明非谐效应会将立方YH₁₀的预测T_c大幅降低至约260-270 K。这些结果强烈否定了二元钇超氢化物中存在室温超导的可能性。
英文摘要
Yttrium polyhydrides are benchmark materials in high-pressure superconductivity, yet several key properties of the Y-H system remain insufficiently characterized. Here we combine contact transport, contactless radio-frequency measurements, pulsed-field experiments, and first-principles calculations to reinvestigate YH$_6$, YH$_9$, and YH$_{10}$ in the pressure range 140-213 GPa. Yttrium hydrides YH$_6$ ($\textit{$T_c$}$ = 218-221 K) and YH$_9$ ($\textit{$T_c$}$ = 235-237 K) demonstrate narrow superconducting transitions ($\textit{$Δ$T$_c$}$ = 2-5 K), approaching the limit imposed by thermal fluctuations. Pulsed-field measurements on YH$_6$ up to 60 T establish an extended superconducting phase diagram with a linear slope $\textit{dB$_{c2}$/dT}$ = -0.52 T/K, pronounced transition broadening above 30 T, and negligible normal-state magnetoresistance. We report the radio-frequency AC susceptibility study of YH$_6$, providing evidence for superconductivity via high-frequency field screening in a contactless geometry. Experiments involving Pd incorporation, Pd thin-film sputtering, and Al alloying show strong suppression of high-temperature superconductivity, with no transitions detected above 78-120 K. Finally, using density-functional theory with the stochastic self-consistent harmonic approximation, superconducting density-functional theory, and full-bandwidth Migdal-Eliashberg calculations, we show that anharmonic effects substantially reduce the predicted $\textit{$T_c$}$ of cubic YH$_{10}$ to approximately 260-270 K. These results strongly disfavor room-temperature superconductivity in binary yttrium superhydrides.
CommentsFigure 4 has been expanded, Fig. S2 has been replaced, and the authors' contributions have been clarified
