Probing the energy gap of high-temperature cuprate superconductors by resonant inelastic x-ray scattering

Hakuto Suzuki (1) , Matteo Minola (1) , Yi Lu (1) , Yingying Peng , Roberto Fumagalli , Emilie Lefrancois (1) , Toshinao Loew (1) , Juan Porras (1) , Kurt Kummer (2) , Davide Betto (2) , Shigeyuki Ishida , Hiroshi Eisaki , Cheng Hu , Xingjiang Zhou , Maurits W. Haverkort , Nicholas B. Brookes (2) , Lucio Braicovich (2) , Giacomo Ghiringhelli , Matthieu Le Tacon (3) , Bernhard Keimer (1)

1 Max-Planck-Institut für Festkörperforschung
2 ESRF - European Synchrotron Radiation Facility
3 KIT - Karlsruher Institut für Technologie

The determination of the symmetry of the energy gap is crucial for research on the microscopic mechanisms of unconventional superconductivity. Here, we demonstrate experimentally that high-resolution resonant inelastic X-ray scattering at the Cu L-3 edge can serve as a momentum-resolved, bulk-sensitive probe of the superconducting gap. We studied two optimally doped cuprates Bi2Sr2CaCu2O8+delta and Bi2Sr2Ca2Cu3O10+delta, in which we observe a strongly momentum dependent reduction of the spectral weight upon entering the superconducting state, with a maximum for momenta connecting antinodal regions of the Fermi surface. Based on a comparison with the calculated charge susceptibility and electronic Raman scattering data, we interpret our observation as a renormalization of the non-local charge susceptibility due to the superconducting gap opening. Our data demonstrate the methodological potential of resonant inelastic X-ray scattering as a versatile probe of the energy gap of high-temperature superconductors, including buried interfaces in heterostructures which are inaccessible to angle-resolved photoemission spectroscopy.

Mots clés: ELECTRONIC RAMAN-SCATTERING; INPLANE SPECTRAL WEIGHT; SINGLE-CRYSTAL GROWTH; T-C; DOPING DEPENDENCE; EXCITATIONS; BI2SR2CACU2O8; STATE

Domaines: Supraconductivité [cond-mat.supr-con]

Hakuto Suzuki, Matteo Minola, Yi Lu, Yingying Peng, Roberto Fumagalli, et al.. Probing the energy gap of high-temperature cuprate superconductors by resonant inelastic x-ray scattering. Npj Quantum Materials, 2018, 3, pp.65. ⟨10.1038/s41535-018-0139-7⟩. ⟨hal-02976815⟩