Abstract

The physics of strongly correlated Fermi systems, being the mainstream topic for more than half a century, still remains elusive. Recent advancements in experimental techniques permit to collect important data, which, in turn, allow us to make the conclusive statements about the underlying physics of strongly correlated Fermi systems. Such systems are close to a special quantum critical point represented by topological fermion-condensation quantum phase transition which separates normal Fermi liquid and that with a fermion condensate, forming flat bands. Our review paper considers recent exciting experimental observations of universal scattering rate related to linear temperature dependence of resistivity in a large number of strongly correlated Fermi systems as well as normal metals. We show that the observed scattering rate is explained by the emergence of flat bands, while the so-called Planckian limit occurs accidentally since the normal metals exhibit the same scattering rate behavior. We also analyze recent challenging experimental data on tunneling differential conductivity collected under the application of magnetic field on the twisted graphene and the archetypical heavy fermion metal YbRh\({}_{2}\)Si\({}_{2}\). Also we describe recent empirical observations of scaling properties related to universal linear-temperature resistivity for a large number of strongly correlated high-temperature superconductors. We show that these observations support the fermion condensation theory. Our theoretical results are in good agreement with corps of different and seemingly unrelated experimental facts. They show that the fermion-condensation quantum phase transition is an intrinsic property of strongly correlated Fermi systems and can be viewed as the universal agent explaining their core physics.

中文翻译：

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支持强相关费米系统的费米凝聚理论的平带和显着实验特征

摘要

高度相关的费米系统的物理学一直是半个多世纪以来的主流话题，但仍然难以捉摸。实验技术的最新进展允许收集重要数据，从而使我们能够对强相关费米系统的基本物理学做出结论性的陈述。这样的系统接近于由拓扑费米-凝聚量子相变表示的特殊量子临界点，该相变将普通费米液体和与费米冷凝物分离的费米液体形成平坦带。我们的评论文章考虑了最近在许多强相关的费米系统以及正常金属中，普遍散射率与电阻率的线性温度相关性的令人兴奋的实验观察结果。我们表明，观察到的散射率是由平坦带的出现所解释的，而所谓​​的普朗克极限是偶然发生的，因为正常金属表现出相同的散射率行为。我们还分析了在扭曲石墨烯和原型重金属费米子金属YbRh上施加磁场后收集的关于隧道差分电导率的最新挑战性实验数据\（{} _ {2} \） Si \（{} _ {2} \）。我们还将描述与大量线性相关的高温超导体的通用线性温度电阻率有关的缩放特性的最新经验观察。我们证明这些观察结果支持费米子凝聚理论。我们的理论结果与不同且看似无关的实验事实的研究小组非常吻合。他们表明，费米子凝聚态量子相变是强相关费米系统的固有特性，可以被视为解释其核心物理的通用剂。