利用初始电荷密度波超导体$2H$-NbS$_2$上的磁性吸附原子探测晶体场调制
Probing crystal-field modulations with magnetic adatoms on the incipient charge-density-wave superconductor $2H$-NbS$_2$
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中文总结 AI 辅助
本研究以$2H$-NbS$_2$为对象，利用磁性吸附原子作为局部传感器，通过操控吸附原子测量YSR激发谱，建立了原子尺度研究晶体场调制的新方法。
中文摘要 AI 辅助
层状材料中多个量子相之间的相互作用可能引发初始量子行为，此时材料的基态接近相变点，对局部无序极为敏感。过渡金属二硫化物材料$2H$-NbS$_2$兼具初始电荷密度波行为与成熟的超导态，形成了局部晶格不稳定性起关键作用的场景。本研究展示了$2H$-NbS$_2$上的单个磁性原子如何用作局部传感器，以揭示隐藏的晶体场调制。通过扫描隧道显微镜针尖操控表面上的吸附原子，我们测量了汤川-柴巴-鲁西诺夫（Yu-Shiba-Rusinov，YSR）激发谱的变化，并绘制了本征点缺陷周围的局部环境。我们发现，尽管超导态在空间上是均匀的，但YSR激发能强烈依赖于原子的位置，确定该效应的主要来源是局部晶体场环境的变化。这些结果建立了一种在原子尺度上研究晶体场调制的新方法，并揭示了缺陷和晶格不稳定性如何塑造初始电荷密度波材料的原子环境。
英文摘要
The interplay between multiple quantum phases in layered materials may lead to incipient quantum behavior, where the material's ground state is close to a phase transition and sensitive to local disorder. The transition metal dichalcogenide material $2H$-NbS$_2$ exhibits incipient charge-density-wave behavior along with a well-developed superconducting state, creating a scenario where the local lattice instabilities play a crucial role. Here we present how an individual magnetic atom on $2H$-NbS$_2$ can be applied as a local sensor to reveal hidden crystal-field modulations. By manipulating the adatom across the surface with the tip of a scanning tunneling microscope, we measure variations in the Yu-Shiba-Rusinov (YSR) excitation spectra and map the local environment around an intrinsic point defect. We find that while the superconducting state is spatially uniform, the YSR excitation energy strongly depends on the position of the atom. We determine that the main contribution to this effect originates from variations in the local crystal-field environment. These results establish a new approach to investigate crystal-field modulations at the atomic scale and reveal how defects and lattice instabilities shape the atomic landscape of an incipient charge-density-wave material.
