Presentation Information
[PC2-02]Low- and High-Energy Charge Excitations of High-Tc Cuprates Probed by Resonant Inelastic X-Ray Scattering
*Takami Tohyama1 (1. Tokyo Univ. of Science (Japan))
Keywords:
RIXS,Charge excitation,Normal and superconducting states
Resonant inelastic X-ray scattering (RIXS) has undergone significant development as a powerful tool for investigating strongly correlated electron systems, such as high-Tc cuprates. In these materials, the characteristic length scale is short due to the localized nature of electrons arising from strong correlation effects. This strong correlation also favors the use of model Hamiltonians over first-principles band structure calculations for describing electronic states. High-energy charge dynamics in high-Tc cuprates typically reflect the local character of the electronic states. Therefore, theoretical approaches based on the t-J and Hubbard models, even within relatively small system sizes, can yield meaningful insights and predictions relevant to RIXS studies [1]. In contrast, low-energy charge dynamics at small momentum transfers are not accessible within such limited system sizes. For these cases, effective model approaches incorporating self-energy effects, either perturbatively or phenomenologically, can provide valuable physical interpretations of RIXS experiments.
For high-energy charge excitations, we investigate the impact of interlayer long-range Coulomb interactions treated within the random phase approximation on the dynamical charge structure factor in the t-J model, calculated using a small-size system. Our results reveal a distinct difference in the spectra between zero and π momenta along the interlayer direction at the lowest in-plane momentum, in agreement with RIXS experiments on high-Tc cuprates.
In the low-energy regime, we examine charge excitations across the superconducting gap at small momenta using a phenomenological tight-binding model that incorporates momentum-dependent anisotropic electron scattering originating from the antinodal region. By comparing the spectra in the superconducting and normal states, we observe a suppression of spectral weight below approximately 80meV in the superconducting state, without any corresponding enhancement at higher energies. These findings are consistent with recent RIXS experiments on optimally doped Bi2Sr2CaCu2O2+δ [2], and highlight the sensitivity of RIXS to the intrinsic electron scatterring in cuprate superconductors.
[1] K. Tsutsui and T. Tohyama, Phys. Rev. B 94, 085144 (2016).
[2] J. Li et al., Phys. Rev. Res. 7, 023319 (2025).
For high-energy charge excitations, we investigate the impact of interlayer long-range Coulomb interactions treated within the random phase approximation on the dynamical charge structure factor in the t-J model, calculated using a small-size system. Our results reveal a distinct difference in the spectra between zero and π momenta along the interlayer direction at the lowest in-plane momentum, in agreement with RIXS experiments on high-Tc cuprates.
In the low-energy regime, we examine charge excitations across the superconducting gap at small momenta using a phenomenological tight-binding model that incorporates momentum-dependent anisotropic electron scattering originating from the antinodal region. By comparing the spectra in the superconducting and normal states, we observe a suppression of spectral weight below approximately 80meV in the superconducting state, without any corresponding enhancement at higher energies. These findings are consistent with recent RIXS experiments on optimally doped Bi2Sr2CaCu2O2+δ [2], and highlight the sensitivity of RIXS to the intrinsic electron scatterring in cuprate superconductors.
[1] K. Tsutsui and T. Tohyama, Phys. Rev. B 94, 085144 (2016).
[2] J. Li et al., Phys. Rev. Res. 7, 023319 (2025).