压力下CsCr₃Sb₅中平带增强的反铁磁涨落与超导性
Flat-Band Enhanced Antiferromagnetic Fluctuations and Superconductivity in Pressurized CsCr$_3$Sb$_5$
AI总结：
针对不同填充水平下kagome体系的自旋动力学与电子有序问题，通过第一性原理计算和随机相位近似分析，研究高压下CsCr₃Sb₅的kagome相自旋涨落与超导不稳定性，揭示其反铁磁涨落及超导序，并提出子晶格-动量耦合驱动机制，为相关体系研究提供新视角。
摘要：
不同填充水平下kagome体系的自旋动力学和电子有序是凝聚态物理中一个引人关注的课题。通过第一性原理计算和随机相位近似分析，我们研究了高压下CsCr₃Sb₅的kagome相中的自旋涨落和超导不稳定性。在略低于kagome平带的填充水平下，我们的计算揭示了CsCr₃Sb₅中强烈的反铁磁自旋涨落，以及主导的sₚₘ₋波和竞争的(dₓᵧ, dₓ²⁻ᵧ²)波超导序。与平带通常与铁磁关联密切相关的普遍直觉不同，我们提出了一种由子晶格-动量耦合驱动的机制，该机制从未占据的平带增强反铁磁涨落。该机制普遍适用于费米能级在平带附近相交的kagome体系，为几何阻挫体系的未来研究提供了新视角。
英文摘要：
The spin dynamics and electronic orders of the kagome system at different filling levels stand as an intriguing subject in condensed matter physics. By first-principles calculations and random phase approximation analyses, we investigate the spin fluctuations and superconducting instabilities in kagome phase of CsCr$_3$Sb$_5$ under high pressure. At the filling level slightly below the kagome flat bands, our calculations reveal strong antiferromagnetic spin fluctuations in CsCr$_3$Sb$_5$, together with a leading $s_{\pm}$-wave and a competing ($d_{xy}$, $d_{x^2-y^2}$)-wave superconducting order. Unlike the general intuition that the flat bands are closely related to the ferromagnetic correlations, here we propose a sublattice-momentum-coupling-driven mechanism for the antiferromagnetic fluctuations enhanced from the unoccupied flat bands. The mechanism is generally applicable to kagome systems where the Fermi level intersects near the flat bands, offering a new perspective for future studies of geometrically frustrated systems.
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