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arXiv 2209.09237cond-mat.str-el
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掺杂 Hubbard 模型中赝能隙的起源与归宿

Origin and fate of the pseudogap in the doped Hubbard model

Fedor Simkovic, Riccardo Rossi, Antoine Georges, Michel Ferrero

AI总结:

本研究利用受控的图蒙特卡罗方法计算了掺杂二维 Hubbard 模型的谱性质,揭示了随掺杂和相互作用变化的三种不同区域,阐明了低掺杂下赝能隙的形成机制,并发现该区域在零温下精确外推至基态的有序条纹相。

摘要:

我们使用受控的图蒙特卡罗计算研究了有限温度下的掺杂二维 Hubbard 模型,该方法允许在无穷大尺寸极限下计算谱性质,且关键在于具有任意动量分辨率。我们表明,作为掺杂和相互作用强度的函数,存在三个不同的区域:性质接近非相互作用系统的弱关联金属、具有强相互作用效应(包括费米面的重塑)的关联金属,以及低掺杂下的赝能隙区域,其中准粒子激发在动量空间的反节点区域附近被选择性地破坏。我们研究了导致赝能隙的物理机制,并表明它既在磁关联长度较大的弱耦合下形成,也在其较短的强耦合下形成。在这两种情况下,我们表明可以修改自旋涨落理论以解释自能非局域分量的行为。我们讨论了温度趋于零时赝能隙的归宿,并表明,值得注意的是,该区域精确外推至由基态方法发现的有序条纹相。这种有限温度与基态结果之间的衔接,极大地推进了对掺杂 Hubbard 模型物理学全面图景的阐述。

英文摘要:

We investigate the doped two-dimensional Hubbard model at finite temperature using controlled diagrammatic Monte Carlo calculations allowing for the computation of spectral properties in the infinite-size limit and, crucially, with arbitrary momentum resolution. We show that three distinct regimes are found as a function of doping and interaction strength, corresponding to a weakly correlated metal with properties close to those of the non-interacting system, a correlated metal with strong interaction effects including a reshaping of the Fermi surface, and a pseudogap regime at low doping in which quasiparticle excitations are selectively destroyed near the antinodal regions of momentum space. We study the physical mechanism leading to the pseudogap and show that it forms both at weak coupling when the magnetic correlation length is large and at strong coupling when it is shorter. In both cases, we show that spin-fluctuation theory can be modified in order to account for the behavior of the non-local component of the self-energy. We discuss the fate of the pseudogap as temperature goes to zero and show that, remarkably, this regime extrapolates precisely to the ordered stripe phase found by ground-state methods. This handshake between finite temperature and ground-state results significantly advances the elaboration of a comprehensive picture of the physics of the doped Hubbard model.

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