Title: Sign changes of the thermoelectric transport coefficient across the metal-insulator crossover in the doped Fermi Hubbard model Show Chinese title

Title: 掺杂费米哈伯德模型中金属-绝缘体转变处的热电输运系数符号变化

Abstract: We investigate the doping-dependence of the Seebeck coefficient, as calculated from the Kelvin formula, for the Fermi Hubbard model using determinantal quantum Monte Carlo simulations. Our key findings are: (1) Besides the expected hole to electron-like behavior change around half filling, we show that the additional sign change at an electronic density $n_s$ (and correspondingly a hole density $p_s$) is controlled by the opening of a charge gap in the thermodynamic density of states or compressibility and not by the pseudogap scale in the single particle density of states. (2) We find that $n_s(T,U)$ depends strongly on the interaction $U$ and shows an unusual non-monotonic dependence on temperature with a maximum at a temperature $T\approx t$, on the order of the hopping scale. (3) We identify local moment formation close to half filling as the main driver for the anomalous behavior of the thermoelectric transport coefficient. Show Chinese abstract

Abstract: 我们研究了用开尔文公式计算的费米哈伯德模型的赛贝克系数随掺杂的变化情况，采用的是确定性量子蒙特卡洛模拟方法。 我们的主要发现如下：（1）除了预期的半满载附近空穴到类似电子的行为变化外，我们还表明，电子密度为$n_s$（相应地，空穴密度为$p_s$）时的额外符号变化是由热力学态密度或可压缩性中的电荷能隙打开所控制，而不是由单粒子态密度中的伪能隙尺度控制。（2）我们发现$n_s(T,U)$对相互作用$U$的依赖性很强，并且在温度上显示出非单调依赖性，在温度$T\approx t$处达到最大值，该温度大约与跳跃尺度相当。（3）我们将近半满载时局域磁矩的形成识别为主要驱动因素，以解释热电输运系数的异常行为。