Probing d-wave superconducting gap of high-Tc cuprate Bi2Sr2Ca2Cu3O10+δ by resonant inelastic X-ray scattering
Abstract
The superconducting gap is a characteristic feature of high-Tc superconductors and provides crucial information on the pairing mechanism underlying high-temperature superconductivity. Here, we employ high-resolution resonant inelastic X-ray scattering (RIXS) at the Cu L3-edge to investigate the superconducting gap in the overdoped cuprate Bi2Sr2Ca2Cu3O10+δ (Tc = 107 K). By analyzing antisymmetrized, temperature-dependent RIXS spectra over a range of in-plane momentum transfers, we observe a clear suppression of low-energy spectral weight below Tc, indicative of superconducting gap formation. This suppression is most pronounced at small momentum transfers (|q| ≤ 0.18 r.l.u.) and corresponds to a gap size of approximately 2Δ0 130 meV. Comparison with theoretical calculations of the momentum-dependent charge susceptibility supports a d-wave symmetry of the superconducting gap, while an isotropic s-wave gap fails to reproduce key experimental features. These findings establish RIXS as a powerful, bulk-sensitive probe of superconducting gap symmetry and highlight its utility for studying materials beyond the reach of surface-sensitive techniques such as ARPES and STM.
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