Strange diffusivity of incoherent metal in half-filled two-dimensional Hubbard model
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866908510524014592 |
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| author | Eom, Youngmin Tupitsyn, Igor S. Prokof'ev, Nikolay V. Svistunov, Boris Kozik, Evgeny Kim, Aaram J. |
| author_facet | Eom, Youngmin Tupitsyn, Igor S. Prokof'ev, Nikolay V. Svistunov, Boris Kozik, Evgeny Kim, Aaram J. |
| contents | We study charge transport across the metal-insulator crossover in the half-filled two-dimensional Hubbard model, with particular emphasis on precision control. The dynamic current-current correlation function is obtained directly in the thermodynamic limit, and the optical conductivity is extracted using numerical analytic continuation. To achieve this, we develop a multiscale approach: the non-perturbative low-frequency behavior is computed using the unbiased diagrammatic Monte Carlo technique, while the high-frequency physics is captured via a self-consistent (semi-)analytic diagrammatic theory. We found that across a broad temperature range where the DC resistivity displays anomalous scaling, $\sim T^α$ with $0<α\lesssim 1$, the Nernst-Einstein relation implies the diffusion constant with the characteristic $\sim 1/\sqrt{T}$ "strange metal" behavior. It was also revealed that the insulating regime is entered through a peculiar non-Fermi liquid state-which we call a Pseudogap Metal-characterized by insulating charge compressibility coexisting with metallic transport. Diagrammatically, the high-temperature incoherent transport is captured by the dressed polarization bubble, whereas near the metal-insulator crossover, the effective interaction vertex between opposite-spin particles is responsible for transferring the Drude weight to a high-frequency continuum. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_00281 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Strange diffusivity of incoherent metal in half-filled two-dimensional Hubbard model Eom, Youngmin Tupitsyn, Igor S. Prokof'ev, Nikolay V. Svistunov, Boris Kozik, Evgeny Kim, Aaram J. Strongly Correlated Electrons Quantum Gases We study charge transport across the metal-insulator crossover in the half-filled two-dimensional Hubbard model, with particular emphasis on precision control. The dynamic current-current correlation function is obtained directly in the thermodynamic limit, and the optical conductivity is extracted using numerical analytic continuation. To achieve this, we develop a multiscale approach: the non-perturbative low-frequency behavior is computed using the unbiased diagrammatic Monte Carlo technique, while the high-frequency physics is captured via a self-consistent (semi-)analytic diagrammatic theory. We found that across a broad temperature range where the DC resistivity displays anomalous scaling, $\sim T^α$ with $0<α\lesssim 1$, the Nernst-Einstein relation implies the diffusion constant with the characteristic $\sim 1/\sqrt{T}$ "strange metal" behavior. It was also revealed that the insulating regime is entered through a peculiar non-Fermi liquid state-which we call a Pseudogap Metal-characterized by insulating charge compressibility coexisting with metallic transport. Diagrammatically, the high-temperature incoherent transport is captured by the dressed polarization bubble, whereas near the metal-insulator crossover, the effective interaction vertex between opposite-spin particles is responsible for transferring the Drude weight to a high-frequency continuum. |
| title | Strange diffusivity of incoherent metal in half-filled two-dimensional Hubbard model |
| topic | Strongly Correlated Electrons Quantum Gases |
| url | https://arxiv.org/abs/2509.00281 |