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arXiv 2602.00833cond-mat.supr-con
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超导氢化物中的位移量子临界点:H₃S的情况

Displacive quantum critical point in superconducting hydrides: The case of H$_3$S

Sorbonne Université(索邦大学);RIKEN Center for Emergent Matter Science(理化学研究所新兴物质科学中心)

Marco Cherubini, Abhishek Raghav, Michele Casula

AI总结:

研究H₃S超导氢化物,用路径积分分子动力学结合基于BLYP密度泛函理论构型训练的MACE神经网络势确定其结构相图,发现位移量子临界点及相关特性,还研究了临界行为及对超导态的影响。

摘要:

H₃S硫化氢因其在约pc = 155 GPa时203 K的高超导临界温度Tc而被广泛研究。尽管是超导氢化物的先驱,但在扩展温度和压力范围内其结构相图的详细情况仍缺失。为确定包括热效应和量子效应的相图,我们进行路径积分分子动力学并结合在BLYP密度泛函理论构型上训练的MACE神经网络势。所得H₃S相图的特征是中心对称Im$\bar{3}$m和极性R3m相之间的位移转变,这源于位于pQCP≈134 GPa的量子临界点(QCP)。我们表明实验Tc峰值落入位移QCP上方大核量子涨落的中心对称区域,通过在虚时中解析的局部声子格林函数测量,其中涨落矩起作用。我们通过有限尺寸标度分析研究系统在QCP附近的临界行为,表明它属于4D伊辛普适类。我们最后讨论其对超导态的影响。

英文摘要:

H$_3$S sulfur hydride has been widely investigated for its high superconducting critical temperature $T_c$ of 203 K at about $p_c = 155$ GPa. Despite being the precursor of superconducting hydrides, a detailed picture of its structural phase diagram in an extended temperature and pressure range is still missing. To determine it with inclusion of both thermal and quantum effects, we carry out path integral molecular dynamics combined to a MACE neural network potential trained on BLYP density functional theory configurations. The resulting H$_3$S phase diagram is characterized by the displacive transition between the centrosymmetric Im$\bar{3}$m and polar R3m phases, which originates from a quantum critical point (QCP) located at $p_\mathrm{QCP} \approx 134$ GPa. We show that the experimental $T_c$ peak falls into a centrosymmetric region of large nuclear quantum fluctuations above the displacive QCP, as measured by local phonon Green's functions resolved in imaginary time, where fluctuating moments are at play. We study the critical behavior of the system in the proximity of the QCP by a finite-size scaling analysis, showing that it belongs to the 4D Ising universality class. We finally discuss its implications for the superconducting state.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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