Li Zejun, Lyu Pin, Chen Zhaolong, Guan Dandan, Yu Shuang, Zhao Jinpei, Huang Pengru, Zhou Xin, Qiu Zhizhan, Fang Hanyan, Hashimoto Makoto, Lu Donghui, Song Fei, Loh Kian Ping, Zheng Yi, Shen Zhi-Xun, Novoselov Kostya S, Lu Jiong
Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, 211189, China.
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Adv Mater. 2024 Jun;36(24):e2312341. doi: 10.1002/adma.202312341. Epub 2024 Apr 11.
Noncentrosymmetric transition metal dichalcogenide (TMD) monolayers offer a fertile platform for exploring unconventional Ising superconductivity (SC) and charge density waves (CDWs). However, the vulnerability of isolated monolayers to structural disorder and environmental oxidation often degrade their electronic coherence. Herein, an alternative approach is reported for fabricating stable and intrinsic monolayers of 1H-TaS sandwiched between SnS blocks in a (SnS)TaS van der Waals (vdW) superlattice. The SnS block layers not only decouple individual 1H-TaS sublayers to endow them with monolayer-like electronic characteristics, but also protect the 1H-TaS layers from electronic degradation. The results reveal the characteristic 3 × 3 CDW order in 1H-TaS sublayers associated with electronic rearrangement in the low-lying sulfur p band, which uncovers a previously undiscovered CDW mechanism rather than the conventional Fermi surface-related framework. Additionally, the (SnS)TaS superlattice exhibits a strongly enhanced Ising-like SC with a layer-independent T of ≈3.0 K, comparable to that of the isolated monolayer 1H-TaS sample, presumably attributed to their monolayer-like characteristics and retained Fermi states. These results provide new insights into the long-debated CDW order and enhanced SC of monolayer 1H-TaS, establishing bulk vdW superlattices as promising platforms for investigating exotic collective quantum phases in the 2D limit.
非中心对称过渡金属二硫属化物（TMD）单层为探索非常规伊辛超导（SC）和电荷密度波（CDW）提供了一个丰富的平台。然而，孤立单层对结构无序和环境氧化的脆弱性常常会降低其电子相干性。在此，报道了一种制备稳定且本征的1H-TaS单层的替代方法，该单层夹在（SnS）TaS范德华（vdW）超晶格的SnS块之间。SnS块层不仅使单个1H-TaS子层解耦，赋予它们类似单层的电子特性，还保护1H-TaS层免受电子降解。结果揭示了1H-TaS子层中与低能硫p带中的电子重排相关的特征性3×3 CDW序，这揭示了一种以前未发现的CDW机制，而不是传统的费米面相关框架。此外，（SnS）TaS超晶格表现出强烈增强的类伊辛超导，其与层无关的转变温度约为3.0 K，与孤立的单层1H-TaS样品相当，这可能归因于它们类似单层的特性和保留的费米态。这些结果为长期以来关于单层1H-TaS的CDW序和增强超导的争论提供了新的见解，确立了体vdW超晶格作为研究二维极限下奇异集体量子相的有前途的平台。
