We use resonant inelastic x-ray scattering (RIXS) to probe the propagation of plasmons in the electron-doped cuprate superconductor Sr0.9La0.1CuO2 (SLCO). We detect a plasmon gap of ∼~120 meV at the two-dimensional Brillouin zone center, indicating that low-energy plasmons in SLCO are not strictly acoustic. The plasmon dispersion, including the gap, is accurately captured by layered t-J-V model calculations. A similar analysis performed on recent RIXS data from other cuprates suggests that the plasmon gap is generic and its size is related to the magnitude of the interlayer hopping tz. Our work signifies the three-dimensionality of the charge dynamics in layered cuprates and provides a new method to determine tz.
@article{arxiv.2206.14083,
title = {Gapped collective charge excitations and interlayer hopping in cuprate superconductors},
author = {M. Hepting and M. Bejas and A. Nag and H. Yamase and N. Coppola and D. Betto and C. Falter and M. Garcia-Fernandez and S. Agrestini and K. -J. Zhou and M. Minola and C. Sacco and L. Maritato and P. Orgiani and H. I. Wei and K. M. Shen and D. G. Schlom and A. Galdi and A. Greco and B. Keimer},
journal= {arXiv preprint arXiv:2206.14083},
year = {2022}
}
Comments
17 pages, 10 figures, includes Supplemental Material. Accepted for publication in Physical Review Letters