Exotic quantum solids can host electronic states that spontaneously break rotational symmetry of the electronic structure, such as electronic nematic phases and unidirectional charge density waves (CDWs). When electrons couple to the lattice, uniaxial strain can be used to anchor and control this electronic directionality. Here, we reveal an unusual impact of strain on unidirectional “smectic” CDW orders in kagome superconductors AV3Sb5 using spectroscopic-imaging scanning tunneling microscopy. We discover local decoupling between the smectic electronic director axis and the direction of anisotropic strain. While the two can generally be aligned along the same direction in regions of a small CDW gap, the tendency for alignment decreases in regions where the CDW gap is the largest. This feature, in turn, suggests nanoscale variations in smectic susceptibility, which we attribute to a combination of local strain and electron correlation strength. Overall, we observe an unusually high decoupling rate between the smectic electronic director of the three-state Potts order and anisotropic strain, revealing weak smectoelastic coupling in the CDW phase of kagome superconductors. This finding is phenomenologically different from the extensively studied nematoelastic coupling in the Ising nematic phase of Ising nematic phase of Fe-based superconductor bulk single crystals, providing a contrasting picture of how strain can control electronic unidirectionality in different families of quantum materials. Published by the American Physical Society 2025

中文翻译：

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Kagome 超导体中纳米级应变和 Smectic 磁化率的相互作用

奇异的量子固体可以承载自发打破电子结构旋转对称性的电子态，例如电子向列相和单向电荷密度波 （CDW）。当电子耦合到晶格上时，可以使用单轴应变来锚定和控制这种电子方向性。在这里，我们使用光谱成像扫描隧道显微镜揭示了应变对笼目超导体 AV3Sb5 中单向“smectic”CDW 阶数的不寻常影响。我们发现 smectic 电子导向轴和各向异性应变方向之间的局部解耦。虽然在 CDW 间隙较小的区域中，两者通常可以沿同一方向对齐，但在 CDW 间隙最大的区域中，对齐的趋势会降低。反过来，这一特征表明 smectic 磁化率的纳米级变化，我们将其归因于局部应变和电子相关强度的结合。总体而言，我们观察到三态 Potts 阶的 smectic 电子导向器与各向异性应变之间的解耦速率异常高，揭示了 kagome 超导体 CDW 相中的微弹性耦合。这一发现在现象学上与广泛研究的 Fe 基超导体体单晶的 Ising 向列相的线弹性耦合不同，为应变如何控制不同量子材料家族中的电子单向性提供了对比图。 美国物理学会 2025 年出版