Quantitative analysis ofSr2RuO4angle-resolved photoemission spectra: Many-body interactions in a model Fermi liquid

Abstract

ARPES spectra hold a wealth of information about the many-body interactions in a correlated material. However, the quantitative analysis of ARPES spectra to extract the various coupling parameters in a consistent manner is extremely challenging, even for a model Fermi liquid system. We propose a fitting procedure which allows quantitative access to the intrinsic lineshape, deconvolved of energy and momentum resolution effects, of the correlated 2-dimensional material Sr2RuO4. For the first time in correlated 2-dimensional materials, we find an ARPES linewidth that is narrower than its binding energy, a key property of quasiparticles within Fermi liquid theory. We also find that when the electron-electron scattering component is separated from the electron-phonon and impurity scattering terms it decreases with a functional form compatible with Fermi liquid theory as the Fermi energy is approached. In combination with the previously determined Fermi surface, these results give the first complete picture of a Fermi liquid system via ARPES. Furthermore, we show that the magnitude of the extracted imaginary part of the self-energy is in remarkable agreement with DC transport measurements.

Self-energy corrections to anisotropic Fermi surfaces

“…The analysis presented here is consistent with the measured Fermi surfaces of the cuprates 9 and qualitatively agrees with the doping evolution reported by ARPES. 4,5,9 The self-energy corrections found for the FS of Sr 2 RuO 4 , which mainly renormalize the ␥ sheet, are as well in qualitative agreement with ARPES measurements 8 and previous calculations. 54 The broad spectrum of experimental data available at this moment makes comparison between results from different techniques one of the most efficient methods to obtain information about response and correlation functions of unconventional materials.…”

“…55 The corrections in the ␣ and ␤ bands are due to curvature effects, while the corrections to the ␥ band are due to Fermi velocity effects, because of the proximity of this band to the saddle points, as has been pointed out above. Then, in agreement with ARPES measurements 8 and other theoretical results, 54 the main corrections induced in the FS of Sr 2 RuO 4 occur at the ␥-band corresponding sheet. The importance of the FS geometry has been analyzed in Ref.…”

“…From the experimental point of view the determination of the scattering rate ͓Im ⌺͑k ជ , ͔͒ presents particular interest and much effort has been devoted in order to obtain it: by ARPES because of the momentum and energy-resolved measurements 8,25,44,45 and recently by electrical transport experiments at microwave frequencies. 46 The extraction of the correlation functions from the experimental data is a complicated task and, although many theoretical approximations exist, the computation of correlation effects is also difficult.…”

“…7 Other transition metal oxides as cobaltates or ruthenates are multiorbital systems and their FS present a complex topology with different sheets derived from the different bands at the Fermi energy. A correlated 2D material particularly interesting is the Sr 2 RuO 4 , a ruthenate considered a model Fermi liquid system with important electronic correlations which have to be taken into account when interpreting photoemission spectra 8 to obtain a clear picture of the electronic properties, especially in the vicinity of the Fermi energy. In Sr 2 RuO 4 the FS separates into three sheets ␣, ␤, and ␥, coming from the d xz , d yz , and d xy orbitals.…”

“…Then, the assumption that the dominant scattering mechanism is the electron-electron interaction in the systems under study is not unreasonable. 8 The essential features of the electron-phonon coupling are explained in Ref. 48, both in the superconducting and normal states.…”