标题： 非相干 regime 中$\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$的各向异性 Seebeck 系数 显示英文标题

标题： Anisotropic Seebeck coefficient of $\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$ in the incoherent regime

摘要： 热电效应的直观熵解释在金属中预测，在非相干区域高温下即使在各向异性金属中也预测各向同性的塞贝克系数，因为熵不是方向性的。 $\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$是一种神秘的材料，以其具有明确表征的各向异性正常态和非常规超导性而闻名。 最近对包含强电子关联效应的$\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$的第一性原理输运计算预测，在300 K以上的高温下塞贝克系数的高温各向异性增强，但缺乏实验证据。 通过对清洁的$\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$单晶在两个晶体学方向上的测量，我们发现随着温度升高至室温，塞贝克系数变得越来越各向同性，这是一般预期的。 然而，在300 K以上，$S$获得了一种新的各向异性，该各向异性上升到所测的最高温度（750 K），这与计算结果定性一致。 这挑战了熵解释，并突显了缺乏一个直观的框架来理解高温下的热电各向异性。 显示英文摘要

摘要： Intuitive entropic interpretations of the thermoelectric effect in metals predict an isotropic Seebeck coefficient at high temperatures in the incoherent regime even in anisotropic metals since entropy is not directional. $\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$ is an enigmatic material known for a well characterised anisotropic normal state and unconventional superconductivity. Recent ab-initio transport calculations of $\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$ that include the effect of strong electronic correlations predicted an enhanced high-temperature anisotropy of the Seebeck coefficient at temperatures above 300 K, but experimental evidence is missing. From measurements on clean $\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$ single crystals along both crystallographic directions, we find that the Seebeck coefficient becomes increasingly isotropic upon heating towards room temperature as generally expected. Above 300 K, however, $S$ acquires a new anisotropy which rises up to the highest temperatures measured (750 K), in qualitative agreement with calculations. This is a challenge to entropic interpretations and highlights the lack of an intuitive framework to understand the anisotropy of thermopower at high temperatures.