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 023231

Evolution 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

More information

Latest update

4/21/2023