P4/mmm型YScH8超导体的量子结构重整化与非谐稳定化
Quantum Structural Renormalization and Anharmonic Stabilization of Superconductivity in P4/mmm YScH8
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- College of Science, Northeast Electric Power University（东北电力大学理学院）
- Xi’an University of Technology（西安工业大学）
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中文总结 AI 辅助
本研究采用随机自洽谐波近似（SSCHA）分析P4/mmm-YScH8的量子与非谐运动效应，发现其可降低动力学稳定阈值压力、修正超导临界温度，明确核量子运动与非谐性对高压三元氢化物超导性预测的必要性。
中文摘要 AI 辅助
近期在191.7 GPa压力下合成的P4/mmm-YScH8，其超导临界温度Tc达113 K，引发了人们对三元超氢化物研究的浓厚兴趣。本研究采用随机自洽谐波近似（SSCHA），系统评估了P4/mmm-YScH8中离子的量子运动与非谐运动效应。研究发现，这些效应会重整化晶体结构，并将动力学稳定阈值压力从约140 GPa降至约84 GPa，降幅约40%；若忽略这些效应，会显著高估Tc，例如在190 GPa时高估约20 K。本研究预测190 GPa下Tc为113 K（μ*=0.13），与实验观测值接近。对声子态密度和Eliashberg谱函数的分析进一步揭示了不同位点对超导性的贡献存在差异。这些结果表明，一致处理核量子运动与非谐性对于准确预测高压三元氢化物的超导性至关重要。
英文摘要
The recent synthesis of P4/mmm-YScH$_{8}$ at 191.7 GPa with a superconducting critical temperature Tc of 113 K has attracted considerable interest in the study of ternary superhydrides. Here we systematically evaluate the effects of quantum and anharmonic motion of ions in P4/mmm-YScH$_{8}$ using the stochastic self-consistent harmonic approximation (SSCHA). We find that these effects renormalize the crystal structure and lower the dynamical stability threshold pressure from $\sim$140 GPa to $\sim$84 GPa, a reduction of about 40%. Furthermore, neglecting these effects causes a significant overestimation of the $T_{c}$, for instance by $\sim$20 K at 190 GPa. Our prediction of $T_{c}$ at 190 GPa is 113 K ($μ^{*}$= 0.13), close to the experimental observation. Analysis of the phonon density of states and Eliashberg spectral function further reveals site-dependent contributions to superconductivity. These results establish that a consistent treatment of nuclear quantum motion and anharmonicity is essential for accurately predicting superconductivity in compressed ternary hydrides.
