Evidence of striped electronic phases in a structurally modulated superlattice

• Published in: Nature (London) 2024-07, Vol.631 (8021), p.526-530
• Main Authors: Devarakonda, A., Chen, A., Fang, S., Graf, D., Kriener, M., Akey, A. J., Bell, D. C., Suzuki, T., Checkelsky, J. G.
• Format: Article
• Language: English
• Subjects: 639/766/119/1003; 639/766/119/995; Bulk density; Critical current (superconductivity); Crystal lattices; Crystals; Electron diffraction; Electron transport; Electrons; Fourier transforms; Gallium arsenide; Heterostructures; Humanities and Social Sciences; Interlayers; Magnetic fields; Magnetic properties; Modulation; multidisciplinary; Oscillations; Phase transitions; Phenomenology; Science; Science (multidisciplinary); Superconductivity; Superlattices; Transition metal compounds; Wave diffraction
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/s41586-024-07589-5

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 1 , exemplified by recent advances in two-dimensional (2D) moiré materials 2 , 3 . Bulk van der Waals (vdW) superlattices 4 – 8 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 SrTa 2 S 5 realizing an incommensurate one-dimensional (1D) structural modulation of 2D transition metal dichalcogenide (TMD) H -TaS 2 layers. High-quality electronic transport in the H -TaS 2 layers, evidenced by quantum oscillations, is made anisotropic by the modulation and exhibits commensurability oscillations paralleling lithographically modulated 2D systems 9 – 11 . We also find unconventional, clean-limit superconductivity in SrTa 2 S 5 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 12 – 14 in SrTa 2 S 5 is spatially modulated and mismatched between adjacent TMD layers. With phenomenology suggestive of pair-density wave superconductivity 15 – 17 , SrTa 2 S 5 may present a pathway for microscopic evaluation of this unconventional order 18 – 21 . More broadly, SrTa 2 S 5 establishes bulk vdW superlattices as versatile platforms to address long-standing predictions surrounding modulated electronic phases in the form of nanoscale vdW devices 12 , 13 to macroscopic crystals 22 , 23 . Evidence of modulated metallic and superconducting states stemming from an incommensurate structural stripe motif is reported in the bulk van der Waals superlattice SrTa 2 S 5 .