Speaker
Description
In recent years, reliable approaches have been developed [1,2] to unambiguously identify the dominant fluctuations driving the multifaceted phenomena of many-electron physics. Among those, the "fluctuation diagnostics" [3] relies on the possibility of expressing the physical quantity of interest in complementary representations. Hitherto, this scheme has been only applied to normal, paramagnetic phases, allowing to pinpoint the spin-fluctuation nature of the pseudogap features in the Hubbard model. After extending the formulation of the fluctuation diagnostics to the superconducting ordered phase, we have applied it [4] to identify the fluctuations responsible for pairing in the d-wave superconducting state of the two-dimensional Hubbard model, solved at intermediate coupling via the dynamical cluster approximation. This way, we could identify antiferromagnetic fluctuations as the ``pairing glue" of the observed superconductivity both in the underdoped and the overdoped regime. However, at the intermediate values of coupling considered, the predominant magnetic fluctuations might significantly differ from those described by conventional spin-fluctuation theory.
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[1] G. Rohringer, Journal of Electron Spectroscopy and Related Phenomena 241, 146804 (2020).
[2] T. Schäfer and A. Toschi, Journal of Physics: Condensed Matter 33, 214001 (2021).
[3] O. Gunnarsson et al., Phys. Rev. Lett. 114, 236402 (2015).
[4] Xinyang Dong, L. del Re, A. Toschi, and E. Gull, submitted (2022).
