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Unraveling intrinsic correlation effects with angle-resolved photoemission spectroscopy

par Anne-Marie - publié le

In collaboration with the Theory group of LSI and experiments performed at the Swiss Light Source we have studied angular resolved satellites in valence band photoelectron spectroscopy. Photoemission spectra reflect the many-body electronic structure of materials. The main peaks whose energies vary as function of angle-resolved momentum usually correspond to the band structure. Replica of these peaks, called satellites, are entirely due to interactions. Therefore, they could be used to detect the strength of electronic correlation in a material, if intrinsic features were not buried by other scattering effects. This study demonstrates how intrinsic satellites can be unraveled from measured spectra using angular resolution and insights on the origin of non-dispersing satellite contributions. A non-dispersing satellite is explained by electron–electron interactions and the thermal motion of the atoms. Additional non dispersing intensity comes from the inelastic scattering of the outgoing photoelectron. The ideal intrinsic spectral function, instead, has satellites that disperse both in energy and in shape. Theory and the information extracted from experiment describe these features with very good agreement.
In the Figure, the images (A) and (C) are calculated spectral functions while (B) is the experimental ARPES image. The results of ab initio GW+C calculations are (A) without and (C) with the Debye-Waller contribution and extrinsic and interference effects.
Angle-resolved photoemission can be used to set an unambiguous lower bound on the strength of correlation.

Ref : J. S. Zhou et al. PNAS (2020)