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Updated: Aug 16, 2026

Piezoreflectance Spectroscopy of Optical Transitions in van der Waals Layered Crystals
Published on: May 22, 2026
Gaplike excitations in the superconducting state of Bi2Sr2CaCu2O8 studied by resonant Raman scattering
D Budelmann1, B Schulz, M Rübhausen
1Institut für Angewandte Physik, Universität Hamburg, D-20355 Hamburg, Germany.
Abstract:
We report on the response of the electronic continuum from inelastic light-scattering experiments over an extended energy range between 1.970 and 4.504 eV in the superconducting state of Bi2Sr2CaCu2O8. The formation of a substantial Raman feature at shifts below twice the superconducting gap as well as the additional weight above this energy are found to be strongly dependent on the incident photon energy. For excitation wavelengths observed in ultraviolet, we find an enhancement of the integrated spectral weight below T(c). The resulting composite feature shows three distinct resonances at 2.5, 3.3, and 3.8 eV. We strongly suggest that the superconductivity-induced changes are the result of both the opening of a superconducting gap and the appearance of a collective mode.
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