@article{031a789ea4f44bfe95bde484b9a36a8f,
title = "Observation of van der Waals phonons in the single-layer cuprate (Bi,Pb)2(Sr,La)2CuO6+δ",
abstract = "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.",
author = "Peng, \{Y. Y.\} and I. Boukahil and K. Krongchon and Q. Xiao and Husain, \{A. A.\} and Sangjun Lee and Li, \{Q. Z.\} and A. Alatas and Said, \{A. H.\} and Yan, \{H. T.\} and Y. Ding and L. Zhao and Zhou, \{X. J.\} and Devereaux, \{T. P.\} and Wagner, \{L. K.\} and Pemmaraju, \{C. D.\} and P. Abbamonte",
note = "This work was supported by the QSQM, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award No. DE-SC0021238. P.A. gratefully acknowledges support from the EPiQS program of the Gordon and Betty Moore Foundation, Grant No. GBMF9452. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. L.K.W. and K.K. were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Computational Materials Sciences program under Award No. DE-SC-0020177 to perform phonon calculations and assist with the analysis. L.Z. and X.J.Z. thank the financial support from the National Natural Science Foundation of China (Grant No. 11888101), the National Key Research and Development Program of China (Grant No. 2016YFA0300300) and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB25000000). Simulation work by I.B., T.P.D., and C.D.P. was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Contract No. DE-AC02-76SF00515 through TIMES at SLAC. Theory simulations used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231.",
year = "2024",
month = feb,
doi = "10.1103/PhysRevMaterials.8.024804",
language = "English (US)",
volume = "8",
journal = "Physical Review Materials",
issn = "2475-9953",
publisher = "American Physical Society",
number = "2",
}