Lenihan Connor, Kim Aaram J, Šimkovic Iv Fedor, Kozik Evgeny
Department of Physics, King's College London, Strand, London WC2R 2LS, United Kingdom.
Centre de Physique Théorique, École Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France.
Phys Rev Lett. 2021 Mar 12;126(10):105701. doi: 10.1103/PhysRevLett.126.105701.
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.
我们研究了正方形晶格上掺杂的哈伯德模型在低温下金属-绝缘体转变附近强电荷和自旋涨落区域的热力学性质，并使用图解蒙特卡罗方法在热力学极限下直接获得了具有可控精度的结果。熵的行为揭示了在半填充附近足够高相互作用时的非费米液体状态：随着耦合强度的增加，非零掺杂时熵出现最大值，并伴有一个拐点，这证明了从金属到非费米液体的转变。比热表现出非费米液体状态的其他独特特征。因此，在光学晶格中用超冷原子进行的量子模拟实验中，熵的测量可以用作探测系统状态的探针。
