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Entropy in the Non-Fermi-Liquid Regime of the Doped 2D Hubbard Model

Connor Lenihan¹, Aaram J Kim¹, Fedor Šimkovic Iv^1,2,3

¹Department of Physics, King's College London, Strand, London WC2R 2LS, United Kingdom.

Physical Review Letters

|March 30, 2021

Abstract:

We study thermodynamic properties of the doped Hubbard model on the square lattice in the regime of strong charge and spin fluctuations at low temperatures near the metal-to-insulator crossover and obtain results with controlled accuracy using the diagrammatic Monte Carlo method directly in the thermodynamic limit. The behavior of the entropy reveals a non-Fermi-liquid state at sufficiently high interactions near half filling: A maximum in the entropy at nonzero doping develops as the coupling strength is increased, along with an inflection point, evidencing a metal to non-Fermi-liquid crossover. The specific heat exhibits additional distinctive features of a non-Fermi-liquid state. Measurements of the entropy can, therefore, be used as a probe of the state of the system in quantum simulation experiments with ultracold atoms in optical lattices.

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