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Disentangling real space fluctuations: The diagnostics of metal-insulator transitions beyond single-particle spectral functions

Michael Meixner1,*, Marcel Krämer1,2,3, Nils Wentzell4, Pietro M. Bonetti1,5, Sabine Andergassen2,3, Alessandro Toschi3, and Thomas Schäfer1,†

  • *Contact author: m.meixner@fkf.mpg.de
  • †Contact author: t.schaefer@fkf.mpg.de
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Phys. Rev. Research 7, 033073 – Published 18 July, 2025

DOI: https://doi.org/10.1103/1nt5-swsk

Abstract

The destruction of metallicity due to the mutual Coulomb interaction of quasiparticles gives rise to fascinating phenomena of solid state physics such as the Mott metal-insulator transition and pseudogap. A key observable characterizing their occurrences is the single-particle spectral function, determined by the fermionic self-energy. In this paper, we investigate in detail how real space fluctuations are responsible for a self-energy that drives the Mott-Hubbard metal-insulator transition. To this aim, we first introduce a real space fluctuation diagnostics approach to the Hedin equation, which connects the fermion-boson coupling vertex λ to the self-energy Σ. Second, by using cellular dynamical mean-field theory calculations, we unambiguously identify nearest-neighbor antiferromagnetic excitations as the leading physical processes responsible for the destruction of metallicity across the transition.

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Phys. Rev. Research 7, 033073– Published 18 July, 2025
  • Received 30 January 2025
  • Accepted 18 June 2025
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