Thermal Signatures of the Slater-Mott Crossover in the Hubbard Model: From Double Occupancy to Antiferromagnetic Correlation Length
Abstract
The interaction-driven crossover from a Slater insulator to a Mott insulator in the Néel-ordered ground state of the Hubbard model is a fundamental paradigm of strongly correlated electrons, yet its quantitative characterization has remained elusive. Here we establish a clear and experimentally accessible thermal criterion for this crossover via the sign change of the temperature derivative of double occupancy, (∂ D/∂ T)U, near zero temperature. In the Slater regime, (∂ D/∂ T)U>0 reflects the major role of charge fluctuations; in the Mott regime, the anomalous (∂ D/∂ T)U<0, a manifestation of the Pomeranchuk effect, signals the dominance of low-energy spin superexchange physics. Using exact diagonalization and {\it numerically exact} quantum Monte Carlo simulations, we demonstrate that this criterion determines the crossover boundary at Ucross/t=4.0(2) for the half-filled two-dimensional Hubbard model. Furthermore, we obtain a consistent boundary independently from the maximum in the antiferromagnetic correlation length, which also arises from the superexchange physics. These two thermal signatures are theoretically unified through the local minimum of thermal entropy versus interaction U at low temperatures. Our results offer a direct, measurable, and physically intuitive framework to identify the Slater-Mott crossover in optical lattice experiments.
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BibTeX
@misc{lu2026thermal,
title = {{Thermal Signatures of the Slater-Mott Crossover in the Hubbard Model: From Double Occupancy to Antiferromagnetic Correlation Length}},
author = {Mingzhong Lu and Yu-Feng Song and Youjin Deng and Yuan-Yao He},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.10976},
eprint = {2606.10976},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.10976},
}
RIS
TY - UNPB
TI - Thermal Signatures of the Slater-Mott Crossover in the Hubbard Model: From Double Occupancy to Antiferromagnetic Correlation Length
AU - Mingzhong Lu
AU - Yu-Feng Song
AU - Youjin Deng
AU - Yuan-Yao He
PY - 2026
DA - 2026/10/12
PB - arXiv
DO - 10.48550/arxiv.2606.10976
UR - https://arxiv.org/abs/2606.10976
AB - The interaction-driven crossover from a Slater insulator to a Mott insulator in the Néel-ordered ground state of the Hubbard model is a fundamental paradigm of strongly correlated electrons, yet its quantitative characterization has remained elusive. Here we establish a clear and experimentally accessible thermal criterion for this crossover via the sign change of the temperature derivative of double occupancy, (∂ D/∂ T)_U, near zero temperature. In the Slater regime, (∂ D/∂ T)_U>0 reflects the major role of charge fluctuations; in the Mott regime, the anomalous (∂ D/∂ T)_U<0, a manifestation of the Pomeranchuk effect, signals the dominance of low-energy spin superexchange physics. Using exact diagonalization and {\it numerically exact} quantum Monte Carlo simulations, we demonstrate that this criterion determines the crossover boundary at U_cross/t=4.0(2) for the half-filled two-dimensional Hubbard model. Furthermore, we obtain a consistent boundary independently from the maximum in the antiferromagnetic correlation length, which also arises from the superexchange physics. These two thermal signatures are theoretically unified through the local minimum of thermal entropy versus interaction U at low temperatures. Our results offer a direct, measurable, and physically intuitive framework to identify the Slater-Mott crossover in optical lattice experiments.
ER -