近日，美国麻省理工学院的J. G. Checkelsky及其研究团队取得一项新进展。经过不懈努力，他们揭示结构调制超晶格中条纹电子相的证据。相关研究成果已于2024年7月3日在国际权威学术期刊《自然》上发表。

该研究团队报道了块体vdW超晶格SrTa₂S₅实现了二维过渡金属二硫化物(TMD) H-TaS₂层的不相称的一维(1D)结构调制。量子振荡证明了H-TaS₂层中的高质量电子输运通过调制变得各向异性，并表现出与光刻调制的二维系统平行的可通约振荡。研究人员还发现SrTa₂S₅中非常规的、干净极限的超导性，相对于层内相干性，层间相干性明显受到抑制。

层间临界电流的面内磁场依赖性以及结构调制的电子衍射表明，SrTa₂S₅的超导性是空间调制的，并且在相邻的TMD层之间不匹配。SrTa₂S₅的现象学暗示了配对密度波超导性，可能为微观评价这种非常规序提供了一种途径。更广泛地说，SrTa₂S₅建立了块体vdW超晶格作为通用平台，以解决围绕纳米级vdW器件到宏观晶体形式的调制电子相的长期预测。

据悉，晶体的电子特性可以通过叠加空间周期性电、磁或结构调制来控制。与原子晶格不相称的长波调制特别有趣，最近二维(2D)莫尔材料的进展就是一个例子。块体范德华(vdW)超晶格承载了最小无序层之间的二维界面，代表了人工vdW异质结构的可扩展块体类似物，并提供了探索不相关调制二维状态的补充场所。

附：英文原文

Title: Evidence of striped electronic phases in a structurally modulated superlattice

Author: Devarakonda, A., Chen, A., Fang, S., Graf, D., Kriener, M., Akey, A. J., Bell, D. C., Suzuki, T., Checkelsky, J. G.

Issue&Volume: 2024-07-03

Abstract: The electronic properties of crystals can be manipulated by superimposing spatially periodic electric, magnetic or structural modulations. Long-wavelength modulations incommensurate with the atomic lattice are particularly interesting, exemplified by recent advances in two-dimensional (2D) moiré materials. Bulk van der Waals (vdW) superlattices hosting 2D interfaces between minimally disordered layers represent scalable bulk analogues of artificial vdW heterostructures and present a complementary venue to explore incommensurately modulated 2D states. Here we report the bulk vdW superlattice SrTa₂S₅ realizing an incommensurate one-dimensional (1D) structural modulation of 2D transition metal dichalcogenide (TMD) H-TaS₂ layers. High-quality electronic transport in the H-TaS₂ layers, evidenced by quantum oscillations, is made anisotropic by the modulation and exhibits commensurability oscillations paralleling lithographically modulated 2D systems. We also find unconventional, clean-limit superconductivity in SrTa₂S₅ with a pronounced suppression of interlayer relative to intralayer coherence. The in-plane magnetic field dependence of interlayer critical current, together with electron diffraction from the structural modulation, suggests superconductivity in SrTa₂S₅ is spatially modulated and mismatched between adjacent TMD layers. With phenomenology suggestive of pair-density wave superconductivity, SrTa₂S₅ may present a pathway for microscopic evaluation of this unconventional order. More broadly, SrTa₂S₅ establishes bulk vdW superlattices as versatile platforms to address long-standing predictions surrounding modulated electronic phases in the form of nanoscale vdW devices to macroscopic crystals.

DOI: 10.1038/s41586-024-07589-5

Source: https://www.nature.com/articles/s41586-024-07589-5