Interaction-enhanced nesting in spin-fermion and Fermi-Hubbard models

Journal Article · Tue Sep 10 00:00:00 EDT 2024 · Physical Review Research

DOI:https://doi.org/10.1103/PhysRevResearch.6.L032058· OSTI ID:2473417

Rossi, R.; IV, F. Šimkovic; Ferrero, M.; Georges, A.; Tsvelik, A. M.; Prokof'ev, N. V.; Tupitsyn, I. S.

The spin-fermion (SF) model postulates that the dominant coupling between low-energy fermions in near critical metals is mediated by collective spin fluctuations (paramagnons) peaked at the Néel wave vector, ${\mathbf{Q}}_N$ , connecting hot spots on opposite sides of the Fermi surface. It has been argued that strong correlations at hot spots lead to a Fermi surface deformation (FSD) featuring flat regions and increased nesting. This conjecture was confirmed in the perturbative self-consistent calculations when the paramagnon propagator dependence on momentum deviation from ${\mathbf{Q}}_N$ is given by ${\chi }^{-1}\propto \left|\mathrm{\Delta }q\right|$ . Using diagrammatic Monte Carlo (diagMC) technique we show that such a dependence holds only at temperatures orders of magnitude smaller than any other energy scale in the problem, indicating that a different mechanism may be at play. Instead, we find that a ${\chi }^{-1}\propto {\left|\mathrm{\Delta }q\right|}^2$ dependence yields a robust finite- $T$ scenario for achieving FSD. To link phenomenological and microscopic descriptions, we applied the connected determinant diagMC method to the $(t-t^{\prime })$ Hubbard model and found that at large $U/t>5.5$ before the formation of electron and hole pockets (i) the FSD defined as a maximum of the spectral function is not very pronounced; instead, it is the lines of zeros of the renormalized dispersion relation that deforms toward nesting, and (ii) the static spin susceptibility is well described by ${\chi }^{-1}\propto {\left|\mathrm{\Delta }q\right|}^2$ . Flat FS regions yield a nontrivial scenario for realizing a non-Fermi liquid state.

Published by the American Physical Society 2024

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0012704; SC0023141
• OSTI ID: 2473417
• Alternate ID(s): OSTI ID: 2472855
• Report Number(s): BNL--226260-2024-JAAM; L032058
• Journal Information: Physical Review Research, Journal Name: Physical Review Research Journal Issue: 3 Vol. 6; ISSN PPRHAI; ISSN 2643-1564
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Diagrammatic methods
Effective field theory
Fermi surface
Feynman diagrams
Magnetic susceptibility
Nesting
Quantum Monte Carlo
Quantum many-body systems
Quasiparticles & collective excitations
Strongly correlated systems
Two-dimensional electron system