Chang Yung-Yeh, Van Nguyen Khoe, Remund Kim, Chung Chung-Hou
Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
Physics Division, National Center for Theoretical Sciences, Taipei 10617, Taiwan.
Rep Prog Phys. 2025 Apr 10;88(4). doi: 10.1088/1361-6633/adc330.
The mysterious metallic phase showing-linear resistivity and a universal scattering rate1/τ=αPkBT/ℏwith a universal prefactorαP∼1and logarithmic-in-temperature singular specific heat coefficient, the so-called 'Planckian metal phase' was observed in various overdoped high-Tccuprate superconductors over a finite range in doping. Revealing the mystery of the Planckian metal state is believed to be the key to understanding the mechanism for high-Tcsuperconductivity. Here, we propose a generic microscopic mechanism for this state based on quantum-critical local bosonic charge Kondo fluctuations coupled to both spinon and a heavy conduction-electron Fermi surface within the heavy-fermion formulation of the slave-boson-model. By a controlled perturbative renormalization group analysis, we examine the competition between the pseudogap phase, characterized by Anderson's Resonating-Valence-Bond spin-liquid, and the Fermi-liquid state, modeled by the electron hopping (effective charge Kondo effect). We find a quantum-critical metallic phase with a universal Planckianℏω/kBTscaling in scattering rate near an extended localized-delocalized (pseudogap-to-Fermi liquid) charge-Kondo breakdown transition. The-wave superconducting ground state emerges near the transition. Unprecedented qualitative and quantitative agreements are reached between our theoretical predictions and various experiments, including optical conductivity, universal doping-independent field-to-temperature scaling in magnetoresistance, specific heat coefficient, marginal Fermi-liquid spectral function observed in ARPES, and Fermi surface reconstruction observed in Hall coefficients in various overdoped cuprates. Our mechanism offers a microscopic understanding of the quantum-critical Planckian metal phase observed in cuprates and its link to the pseudogap,-wave superconducting, and Fermi liquid phases. It offers a promising route for understanding how-wave superconductivity emerges from such a strange metal phase in cuprates-one of the long-standing open problems in condensed matter physics since 1990s-as well as shows a broader implication for the Planckian strange metal states observed in other correlated unconventional superconductors.
在各种过掺杂的高温铜酸盐超导体的有限掺杂范围内，观察到了神秘的金属相，其呈现线性电阻率和通用散射率1/τ = αPkBT/ℏ，其中通用 prefactorαP ∼ 1且比热系数具有对数温度奇异特性，即所谓的“普朗克金属相”。揭示普朗克金属态的奥秘被认为是理解高温超导机制的关键。在此，我们基于量子临界局部玻色子电荷近藤涨落，在从玻色子模型的重费米子表述中，提出了一种针对该状态的通用微观机制，该涨落与自旋子和重传导电子费米面都耦合。通过可控的微扰重整化群分析，我们研究了以安德森共振价键自旋液体为特征的赝能隙相和以电子跳跃（有效电荷近藤效应）为模型的费米液体态之间的竞争。我们发现在扩展的局域 - 非局域（赝能隙到费米液体）电荷近藤击穿转变附近，存在一个具有通用普朗克ℏω/kBT散射率标度的量子临界金属相。波超导基态在该转变附近出现。我们的理论预测与各种实验之间达成了前所未有的定性和定量一致，包括光导率、磁阻中与掺杂无关的通用场 - 温度标度、比热系数、角分辨光电子能谱中观察到的边缘费米液体谱函数以及各种过掺杂铜酸盐中霍尔系数观察到的费米面重构。我们的机制为在铜酸盐中观察到的量子临界普朗克金属相及其与赝能隙、波超导和费米液体相的联系提供了微观理解。它为理解自20世纪90年代以来凝聚态物理中一个长期存在的开放问题——铜酸盐中波超导如何从这样一个奇异金属相中出现——提供了一条有希望的途径，同时也对在其他相关非传统超导体中观察到的普朗克奇异金属态具有更广泛的意义。
