Determining the electron-phonon coupling in superconducting cuprates by resonant inelastic x-ray scattering: Methods and results on Nd1+xBa2-xCu3O7-δ
Journal article, 2020
The coupling between lattice vibration quanta and valence electrons can induce charge-density modulations and decisively influence the transport properties of materials, e.g., leading to conventional superconductivity. In high-critical-temperature superconductors, where electronic correlation is the main actor, the actual role of electron-phonon coupling (EPC) is being intensely debated theoretically and investigated experimentally. We present an in-depth study of how the EPC strength can be obtained directly from resonant inelastic x-ray scattering (RIXS) data through the theoretical approach derived by Ament et al. [Europhys. Lett. 95, 27008 (2011)]. The role of the model parameters (e.g., phonon energy ω0, intermediate state lifetime 1/Γ, EPC matrix element M, and detuning energy Ω) is thoroughly analyzed, providing general relations among them that can be used to make quantitative estimates of the dimensionless EPC g=(M/ω0)2 without detailed microscopic modeling. We then apply these methods to very high-resolution Cu L3-edge RIXS spectra of three Nd1+xBa2−xCu3O7−δ films. For the insulating antiferromagnetic parent compound, the value of M as a function of the in-plane momentum transfer is obtained for Cu-O bond-stretching (breathing) and bond-bending (buckling) phonon branches. For the underdoped and the nearly optimally doped samples, the effects of Coulomb screening and of charge-density-wave correlations on M are assessed. In light of the anticipated further improvements of the RIXS experimental resolution, this work provides a solid framework for an exhaustive investigation of the EPC in cuprates and other quantum materials.
Author
Lucio Braicovich
European Synchrotron Radiation Facility (ESRF)
Polytechnic University of Milan
Matteo Rossi
Polytechnic University of Milan
Roberto Fumagalli
Polytechnic University of Milan
Y. Y. Peng
Polytechnic University of Milan
Yan Wang
University of Tennessee
Riccardo Arpaia
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Davide Betto
European Synchrotron Radiation Facility (ESRF)
Gabriella M. De Luca
University of Naples Federico II
CNR SPIN Institute - Napoli
D. Di Castro
University of Rome Tor Vergata
Kurt Kummer
European Synchrotron Radiation Facility (ESRF)
Marco Moretti Sala
Polytechnic University of Milan
Mattia Pagetti
Polytechnic University of Milan
G Balestrino
University of Rome Tor Vergata
Nicholas B. Brookes
European Synchrotron Radiation Facility (ESRF)
Marco Salluzzo
CNR SPIN Institute - Napoli
S. Johnston
Leibniz Institute for Solid State and Materials Research Dresedn
University of Tennessee
J. van den Brink
Leibniz Institute for Solid State and Materials Research Dresedn
Washington University in St. Louis
Technische Universität Dresden
Giacomo Ghiringhelli
Polytechnic University of Milan
Physical Review Research
26431564 (ISSN)
Vol. 2 2 023231Evolution of nanoscale charge order in superconducting YBCO nanostructures
Swedish Research Council (VR) (2017-00382), 2017-07-01 -- 2020-06-30.
Subject Categories
Condensed Matter Physics
DOI
10.1103/PhysRevResearch.2.023231