Motivated by the recent proposal that the Monte Carlo sign problem might be used as an indicator of quantum phase transitions, we simulate the periodic Anderson model at half-filling with a staggered ionic potential using the determinant quantum Monte Carlo (DQMC) approach. We observe a phase transition from a band insulator to a Kondo insulator as the hybridization increases. At finite temperature, an intermediate metallic region emerges between two insulating phases, which is characterized by a pseudogap in the spectral functions near the boundary of the intermediate region and a quasiparticle peak in the middle. The latter coincides with a crossing point of the 𝑓-electron occupation on different sublattices as well as the maximum antiferromagnetic (AFM) correlations. The metallic region extrapolates to a single quantum critical point at zero temperature, which may result in exotic quasiparticle excitations associated with the emergent metallic state. The Monte Carlo sign problem is found to be most pronounced in the quantum critical region, implying a close connection between the two phenomena. Our results are qualitatively supported by the Hartree-Fock (HF) mean-field calculations. Our work reveals interesting physics in inhomogeneous Kondo lattice systems that may be worthwhile of more investigations in the future.

中文翻译：

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交错电位周期性 Anderson 模型中的绝缘体到绝缘体转变和符号问题


受最近提出的蒙特卡洛符号问题可能用作量子相变指标的启发，我们使用行列式量子蒙特卡洛 （DQMC） 方法模拟了具有交错离子势的半填充周期性安德森模型。随着杂化的增加，我们观察到从带绝缘体到 Kondo 绝缘体的相变。在有限温度下，在两个绝缘相之间出现一个中间金属区，其特征是在中间区边界附近出现光谱函数中的伪间隙，在中间出现准粒子峰。后者与 f 电子在不同亚晶格上的占据以及最大反铁磁 （AFM） 相关性相吻合。金属区域在零温度下外推到单个量子临界点，这可能导致与新兴金属态相关的奇异准粒子激发。蒙特卡洛符号问题在量子临界区最为明显，这意味着这两种现象之间存在密切联系。我们的结果得到了 Hartree-Fock （HF） 平均场计算的定性支持。我们的工作揭示了非均匀 Kondo 晶格系统中有趣的物理学，可能值得在未来进行更多研究。