Observation of van der Waals phonons in the single-layer cuprate (Bi,Pb)2(Sr,La)2CuO6+δ

Y. Y. Peng, I. Boukahil, K. Krongchon, Q. Xiao, A. A. Husain, Sangjun Lee, Q. Z. Li, A. Alatas, A. H. Said, H. T. Yan, Y. Ding, L. Zhao, X. J. Zhou, T. P. Devereaux, L. K. Wagner, C. D. Pemmaraju, P. Abbamonte

Research output: Contribution to journalArticlepeer-review


Interlayer van der Waals (vdW) coupling is generic in two-dimensional materials such as graphene and transition-metal dichalcogenides, which can induce very low-energy phonon modes. Using high-resolution inelastic hard x-ray scattering, we uncover the ultralow energy phonon mode along the Cu-O bond direction in the high-Tc cuprate (Bi,Pb)2(Sr,La)2CuO6+δ (Bi2201). The energy and full-width half-maximum (FWHM) of these modes are independent of temperature, while their intensity decreases with doping in accordance with an increasing c-axis lattice parameter. We compare the experimental results to first-principles density functional theory simulations and identify the observed mode as a van der Waals phonon, which arises from the shear motion of the adjacent Bi-O layers. This shows that Bi-based cuprate has vibrational properties similar to graphene and transition-metal dichalcogenides, which can be exploited to engineer novel heterostructures.

Original languageEnglish (US)
Article number024804
JournalPhysical Review Materials
Issue number2
StatePublished - Feb 2024
Externally publishedYes

ASJC Scopus subject areas

  • General Materials Science
  • Physics and Astronomy (miscellaneous)


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