Abstract
Recently discovered superconductors AV3Sb5 (A = K, Rb, Cs)1,2 provide a fresh opportunity to study correlation-driven electronic phenomena on a kagome lattice. The observation of an unusual charge density wave (CDW) in the normal state of all the members of the AV3Sb5 family2–10 has prompted a large effort to identify any ‘hidden’ broken symmetries associated with it. We use spectroscopic-imaging scanning tunnelling microscopy to reveal pronounced intensity anisotropy between the different directions of hexagonal CDW in KV3Sb5. In particular, we find that one of the CDW directions is distinctly different compared with the other two. This observation points to an intrinsic rotation-symmetry-broken electronic ground state where the symmetry is reduced from sixfold to twofold. Furthermore, in contrast to previous reports3, we find that the CDW phase is insensitive to the magnetic-field direction, regardless of the presence or absence of atomic defects. Our experiments, combined with earlier observations of stripe charge ordering in CsV3Sb5, establish correlation-driven rotation symmetry breaking as a unifying feature of AV3Sb5 kagome superconductors.
| Original language | English |
|---|---|
| Pages (from-to) | 265-270 |
| Number of pages | 6 |
| Journal | Nature Physics |
| Volume | 18 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2022 |
Funding
We thank A. Soumyanarayanan and J. E. Hoffman for providing the NbSe2 STM data used for analysis in Extended Data Fig. 4. We are also thankful to Rafael Fernandes for insightful conversations. I.Z. gratefully acknowledges support from the National Science Foundation grant NSF-DMR-1654041 and Boston College startup. S.D.W., B.R.O. and T.P. acknowledge support from the University of California Santa Barbara (UCSB) NSF Quantum Foundry funded via the Quantum Materials Science, Engineering and Information (Q-AMASE-i) program under award DMR-1906325. B.R.O. also acknowledges support from the California NanoSystems Institute through the Elings Fellowship program. Z.W. acknowledges support from the US Department of Energy, Basic Energy Sciences, grant no. DE-FG02-99ER45747 and the Cottrell SEED Award no. 27856 from the Research Corporation for Science Advancement. L.B. is supported by the NSF CMMT program under grant no. DMR-2116515. M.Y. is supported in part by the Gordon and Betty Moore Foundation through grant GBMF8690 to UCSB and by the National Science Foundation under grant no. NSF PHY-1748958. T.P. was supported by the National Science Foundation through Enabling Quantum Leap: Convergent Accelerated Discovery Foundries for Q-AMASE-i under award no. DMR-1906325.