The apparent Fermi liquid concept helps to understand thermoelectric materials
Andrzej M. Oleś
关于S条的特邀专家意见。Kremer和R. Fresard，Ann.Phys.（Berlin）524，21（2012）.
Invited expert opinion on the article S. Kremer and R. Fresard, Ann. Phys. (Berlin) 524, 21 (2012).
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Evidence for energy-dependent scattering dominating thermoelectricity in heavy fermion systems
本文利用角分辨光电子能谱证明重费米子准粒子弛豫时间在Fermi能级附近高度依赖能量，该能量依赖性源于相干Kondo散射，能合理描述Seebeck系数符号，为关联材料热电性理解及轨道选择性工程提供新视角。
Fermi Surface Reconstruction inside the Hidden Order Phase of URu2Si2 Probed by Thermoelectric Measurements
我们报告的热电测量低载流子重费米子化合物URu 2Si 2在高场高达34 T，在低温下至500 mK。场的热电功率（TEP）和能斯特信号的依赖性显示连续的异常深处的隐藏顺序（HO）阶段。这些异常的场位置对应于12 T、17 T、23 T和30 T附近Shubnikov-de Haas频率和有效质量的不同变化。这些结果表明连续重建的费米面，这意味着电子相变以及HO阶段内。
Sign changes of the thermoelectric transport coefficient across the metal-insulator crossover in the doped Fermi Hubbard model
本研究通过量子蒙特卡罗模拟，发现掺杂费米哈伯德模型中塞贝克系数的额外符号变化由电荷隙控制，而非赝隙，且局域矩形成是异常热电输运的主要驱动因素。
General Formula for the Thermoelectric Transport Phenomena based on the Fermi Liquid Theory: Thermopower, Nernst Coefficient, and Thermal Conductivity
在线性响应输运理论的基础上，利用费米液体理论，导出了热电功率（S）、能斯特系数（ν）和热导率（κ）等热电输运系数的一般表达式。对于最奇异项，所得到的表达式是精确的，它表示为1/γ_k^*（γ_k^* 为准粒子阻尼率）。我们利用由局部能量守恒定律导出的热流的沃德恒等式。基于导出的表达式，我们可以计算各种热电输运系数的框架内的Baym-Kadanoff型守恒近似。因此，这些表达式对于研究高T_c超导体、有机金属、重费米子系统等强关联电子，特别是其中电流顶点修正将发挥重要作用的电子，是非常有用的.利用导出的表达式，我们计算了自由色散模型中关于U的二阶热导率κ。我们发现，尽管电子流的顶点修正使系统的电导率（σ）发散，反映了Umklapp过程的不存在，但由于热流的顶点修正，电导率略有增强。
Thermoelectric power of Ba(Fe1-xRux)2As2 and Ba(Fe1-xCox)2As2: possible changes of Fermi surface with and without changes in electron count
本文给出了Ba（Fe_（1-x）Rux）_2As_2（0 < x < 0.36）单晶的面内热电功率（TEP）随温度变化的数据。证实了以前所提出的该体系的x-T相图.与Ru掺杂的TEP演变的分析表明，在电子结构，相关性和/或散射发生的约7%和约30%的Ru掺杂水平附近的显着变化。这些结果进行了比较与一组扩展的TEP数据的电子掺杂的Ba（Fe 1-xCox）2As 2系列。
Quantum dot devices allow one to access the critical point of the two-channel Kondo model. The effective critical theory involves a free Majorana fermion quasiparticle localized on the dot. As a consequence, this critical point shows both the phenomenon of non-Fermi liquid physics and fractionalization. Although a violation of the Wiedemann-Franz law is considered a defining feature of non-Fermi liquid systems, we show by exact calculations that it holds at the critical point, providing a counterexample to this lore. Furthermore, we show that the fractionalized Majorana character of the critic…
We study thermoelectric transport properties of fractional quantum Hall systems based on exact diagonalization calculation. Based on the relation between thermoelectric response and thermal entropy, we demonstrate that thermoelectric Hall conductivity $α_{xy}$ has powerlaw scaling $α_{xy} \propto T^η$ for gapless composite Fermi-liquid states at filling number $ν=1/2$ and $1/4$ at low temperature ($T$), with exponent $η\sim 0.5$ distinctly different from Fermi liquids. The powerlaw scaling remains unchanged for different forms of interaction including Coulomb and short-range ones, demonstratin…
Searching for high-performance thermoelectric (TE) materials in the paradigm of narrow-bandgap semiconductors has lasted for nearly 70 years and is obviously hampered by a bottleneck of research now. Here we report on the discovery of a few metallic compounds, TiFexCu2x-1Sb and TiFe1.33Sb, showing the thermopower exceeding many TE semiconductors and the dimensionless figure of merits comparable with the state-of-the-art TE materials. A quasi-linear temperature (T) dependence of electrical resistivity in 2 K - 700 K and the logarithmic T-dependent electronic specific heat at low temperature are…
We develop a conformal-field theory approach for investigation of the quantum charge-, heat- and thermoelectric- transport through a quantum impurity fine tuned to a non-Fermi liquid regime. The non-Fermi-liquid operational mode is associated with the overscreened spin Kondo effect and controlled by the number of orbital channels. The universal low-temperature scaling and critical exponents for Seebeck and Peltier coefficients are investigated for the multichannel geometry. We derive and analyze the universal dependence of the thermoelectric coefficients on the number of orbital channels. We d…
We report on low-energy electronic structure and electronic correlations of K$_{0.65}$RhO$_2$, studied using high-resolution angle-resolved photoemission spectroscopy (ARPES) technique and density functional theory (DFT) calculations. We observe a highly correlated hole pocket on the Fermi surface. We further notice that the correlations are momentum dependent. Most importantly, two $kinks$ at binding energies of 75 meV and 195 meV have been observed from the band dispersion in the vicinity of the Fermi level. While the low energy $kink$ at 75 meV can be understood as a result of the electron-…
Thermoelectric materials can be used to convert heat to electric power through the Seebeck effect. We study magneto-thermoelectric figure of merit (ZT) in three-dimensional Dirac semimetal Cd$_3$As$_2$ crystal. It is found that enhancement of power factor and reduction of thermal conductivity can be realized at the same time through magnetic field although magnetoresistivity is greatly increased. ZT can be highly enhanced from 0.17 to 1.1 by more than six times around 350 K under a perpendicular magnetic field of 7 Tesla. The huge enhancement of ZT by magnetic field arises from the linear Dira…
Thermoelectric and thermal properties of the weakly disordered non-Fermi liquid phase of Luttinger semimetals
本研究采用Mori-Zwanzig记忆矩阵方法，计算了Luttinger半金属弱无序非费米液相的热电与热输运特性，得到了热导率和热电系数的低温标度关系，为识别该非费米液态提供关键特征，也为热电应用候选材料提供了参考。
Thermoelectric Transport through a Quantum Dot: Effects of Kondo Channels Asymmetry
本文研究了磁场对单电子晶体管热电势和热导的影响，该晶体管由一个量子点通过单模量子点接触与其中一个引线强耦合而成。我们发现了两个新的能量标度：T_{min} ~ |r| ^2 E_C（B/B_C）^2依赖于磁场B和场B_C的比值，对应于点接触的全极化; T_{max} ~ |r| ^2 E_C依赖于反射振幅r和充电能量E_C。在T T_{min}时，热电系数的行为符合费米液体理论，而在T_{min} <T< T_{max}时，热电系数从非费米液体的双通道近藤效应过渡到费米液体的单通道近藤效应.
Thermoelectric properties of iron-based superconductors and parent compounds
在此，我们回顾了铁基超导体及其母体化合物热电输运性质的实验数据。我们讨论了可能的物理机制发挥作用，在确定塞贝克效应，从中可以提取有关费米面重建和Lifshitz转换，多带字符，耦合的载流子与自旋激发和它的相关性在非常规超导配对机制，向列性，量子临界波动接近超导性的最佳掺杂，相关性的信息。从能斯特效应的分析中获得了额外的信息，其在母体化合物中的增强必须部分地与多带传输和低费米能级有关，但主要是与费米能级处的狄拉克锥带的存在有关。在超导化合物中，正常态下的能斯特效应可以用自旋密度波态的涨落前兆来解释，而超导态下的能斯特效应则反映了通常的涡旋液体耗散机制。不同家族的铁基超导体和母体化合物的热电行为的现象学之间的比较可以证明关键的差异和类比，从而为这些迷人的非常规超导体的丰富而复杂的物理学提供线索。
We calculate the thermoelectric response coefficients of three-dimensional Dirac or Weyl semimetals as a function of magnetic field, temperature, and Fermi energy. We focus in particular on the thermoelectric Hall coefficient $α_{xy}$ and the Seebeck coefficient $S_{xx}$, which are well-defined even in the dissipationless limit. We contrast the behaviors of $α_{xy}$ and $S_{xx}$ with those of traditional Schrödinger particle systems, such as doped semiconductors. Strikingly, we find that for Dirac materials $α_{xy}$ acquires a constant, quantized value at sufficiently large magnetic field, whi…
For the fractional quantum Hall states on a finite disc, we study the thermoelectric transport properties under the influence of an edge and its reconstruction. In a recent study on a torus [Phys. Rev. B 101, 241101 (2020)], Sheng and Fu found a universal non-Fermi liquid power-law scaling of the thermoelectric conductivity $α_{xy} \propto T^η$ for the gapless composite Fermi-liquid state. The exponent $η\sim 0.5$ appears an independence of the filling factors and the details of the interactions. In the presence of an edge, we find the properties of the edge spectrum dominants the low-temperat…
Thermoelectric signature of quantum criticality in the heavy-fermion superconductor CeRhIn$_5$
本研究通过热电势测量发现纯 CeRhIn$_5$ 在 Kondo 破缺 QCP 处发生热电势剧烈坍缩，而 4.4% Sn 掺杂样品在自旋密度波 QCP 附近呈对称行为，证明热电势可有效区分重费米子系统的量子临界性本质。
Transverse Thermoelectric Response as a Probe for Existence of Quasiparticles
具有反射对称性的各向异性相互作用系统的霍尔电导率服从sigma_{xy} = - sigma_{yx}。相反，我们表明，横向热电Peltier系数之间的类似关系，alpha_{xy} = - alpha_{yx}，一般不成立，在同一系统。这一事实可以追溯到相互作用的热流算子和热电响应函数的混合性质的贡献。然而，值得注意的是，低温下准粒子的出现似乎迫使alpha_{xy} = - alpha_{yx}。这表明，准粒子自由基态（所谓的非费米液体）可以通过检查之间的关系alpha_{xy}和alpha_{yx}在反射对称性和微观各向异性的存在下检测。这些结论是基于以下结果：（i）弹性散射的非相互作用粒子的珀耳帖系数之间的关系是准确的;（ii）它保持近似玻尔兹曼理论的相互作用粒子时，弹性散射占主导地位的非弹性过程。在无序的费米液体中，后者导致的偏差以T^3的形式消失。(iii)我们计算了热电响应的弱耦合自旋能隙的Luttinger液体的模型，并获得了强烈的非对角分量之间的反对称性的破坏。我们还发现，在这个模型中的能斯特信号被增强的相互作用，并可以改变的磁场和温度的函数的符号。
Quantum strongly correlated matter exhibits properties which are not easily explainable in the conventional framework of Fermi liquids. Universal effective field theory tools are applicable in these cases regardless of the microscopic details of the quantum system, since they are based on symmetries. It is necessary, however, to construct these effective tools in full generality, avoiding restrictions coming from particular microscopic descriptions which may inadequately constrain the coefficients that enter in the effective theory. In this work we demonstrate on explicit examples how the nove…
Protection of a non-Fermi liquid by spin-orbit interaction
我们表明，热电输运通过量子点（QD）-单模量子点接触（QPC）纳米器件，表现出明显的指纹的非费米液体（NFL）的行为，在没有外部磁场的情况下，保护从磁场NFL破坏强自旋轨道相互作用（SOI）。的保护机制是与外观的额外的散射过程，由于缺乏自旋守恒在SOI和小塞曼场的存在下。面内磁场$\vec B$和SOI之间的相互作用由$\vec B$和$\vec B_{SOI}$之间的角度控制。我们预测热电系数对磁场方向的强烈依赖性，并讨论了NFL效应实验观察的参数窗口。
We use quantum kinetic theory to calculate the thermoelectric transport properties of the 2D single band Fermi-Hubbard model in the weak coupling limit. For generic filling, we find that the high-temperature limiting behaviors of the electrical ($\sim T$) and thermal ($\sim T^2$) resistivities persist down to temperatures of order the hopping matrix element $T\sim t$, almost an order of magnitude below the bandwidth. At half filling, perfect nesting leads to anomalous low temperature scattering and nearly $T$-linear electrical resistivity at all temperatures. We hypothesize that the $T$-linear…
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