标题： 非线性热电效应作为探测量子几何的手段 显示英文标题

标题： Nonlinear thermoelectric effects as a means to probe quantum geometry

摘要： 量子几何张量，作为量子度规和Berry曲率的实部和虚部，在凝聚态系统输运性质中起着关键作用。在非线性区域，量子度规偶极子和Berry曲率偶极子提供了两种产生非线性霍尔效应的不同机制，这些都可以在具有合适对称性的系统中通过实验观察到。在这项工作中，我们研究了量子几何在非线性热电响应中的作用。我们分别推导了一系列由Berry曲率偶极子和量子度规偶极子控制的非线性热电效应。其中，我们识别出一种特别有趣的量化热电响应，它直接测量费米能级以下Weyl点的总手性。对于一般的非线性响应，我们推导了Wiedemann-Franz定律和Mott公式对应的非线性版本。这些提供了一种基于现有非线性霍尔测量来估计非线性热电响应幅度的方法。我们的估算表明，这些效应应该可以在几种候选材料中观测到，其中In掺杂的Pb$_{1-x}$Sn$_x$Te显得最为有希望。我们的工作通过非线性热电测量为量子几何的实验研究提供了新的见解。 显示英文摘要

摘要： The quantum geometric tensor, which has the quantum metric and Berry curvature as its real and imaginary parts, plays a key role in the transport properties of condensed matter systems. In the nonlinear regime, the quantum metric dipole and Berry curvature dipole provide two distinct mechanisms for generating nonlinear Hall effects, which can both be experimentally observed in systems with suitable symmetries. In this work, we investigate the role of quantum geometry in nonlinear thermoelectric responses. We derive a series of nonlinear thermoelectric effects governed by the Berry curvature dipole and the quantum metric dipole, respectively. Among them, we identify a particularly interesting quantized thermoelectric response that directly measures the total chirality of Weyl points below the Fermi level. For general nonlinear responses, we derive the nonlinear analogs of the Wiedemann-Franz law and Mott's formula. These provide a means to estimate the magnitude of nonlinear thermoelectric responses based on existing nonlinear Hall measurements. Our estimates suggest that these effects should be observable in several candidate materials, with In-doped Pb$_{1-x}$Sn$_x$Te standing out as the most promising. Our work offers new insights into the experimental study of quantum geometry through nonlinear thermoelectric measurements.