Discovery of a Cooper-pair density wave state in a transition-metal dichalcogenide
Abstract
Pair density wave (PDW) states are defined by a spatially modulating superconductive order parameter. To search for such states in transition-metal dichalcogenides (TMDs), we used high-speed atomic-resolution scanned Josephson-tunneling microscopy. We detected a PDW state whose electron-pair density and energy gap modulate spatially at the wave vectors of the preexisting charge density wave (CDW) state. The PDW couples linearly to both the s-wave superconductor and the CDW and exhibits commensurate domains with discommensuration phase slips at the boundaries, conforming those of the lattice-locked commensurate CDW. Nevertheless, we found a global δΦ≅±2π/3 phase difference between the PDW and CDW states, possibly owing to the Cooper-pair wave function orbital content. Our findings presage pervasive PDW physics in the many other TMDs that sustain both CDW and superconducting states.
- Publication:
-
Science
- Pub Date:
- June 2021
- DOI:
- 10.1126/science.abd4607
- arXiv:
- arXiv:2007.15228
- Bibcode:
- 2021Sci...372.1447L
- Keywords:
-
- PHYSICS;
- Condensed Matter - Superconductivity
- E-Print:
- Science 2021, 372, 1447-1452