We study the Kondo alloy model on a square lattice using dynamical mean-field theory (DMFT) for Kondo substitution and disorder effects, together with static mean-field approximations. We computed and analyzed photoemission properties as a function of electronic filling $n_c$, Kondo impurity concentration $x$, and strength of Kondo temperature $T_K$. We provide a complete description of the Angle Resolved Photoemission Spectroscopy (ARPES) signals expected in the paramagnetic Kondo phases. By analyzing the Fermi surface, we observe the Lifshitz-like transition predicted previously for strong $T_K$ at $x=n_c$ and we discuss the evolution of the dispersion from the dense coherent to the dilute Kondo regimes. At smaller $T_K$, we find that this transition marking the breakdown of coherence at $x=n_c$ becomes a crossover. However, we identify another transition at a smaller concentration $x^\star$ where the effective mass continuously vanishes. $x^\star$ separates the one-branch and the two-branches ARPES dispersions characterizing respectively dilute and dense Kondo paramagnetic regimes. The $x-T_K$ phase diagrams are also described, suggesting that the transition at $x^\star$ might be experimentally observable since magnetically ordered phases are stabilized at much lower $T_K$. Fermi surface reconstructions in antiferromagnetic and ferromagnetic phases are also discussed.
The thermopower as a fingerprint of the Kondo breakdown quantum critical point
我们提出,热电势区分两个竞争的情况下,量子相变在重费米子:自旋密度波(SDW)理论和击穿的近藤效应。在近藤崩溃的情况下,塞贝克系数原来从温度标度$E^{*}$,与费米表面重构的量子涨落崩溃。这一特征与SDW理论的物理性质有着根本的不同,在SDW理论中,费米面不会发生重构,这一特征可以被认为是近藤击穿理论的标志。我们测试这些想法,对YbRh $_2$ Si $_2$的实验结果。
Fermi Surface Reconstruction without Breakdown of Kondo Screening at Quantum Critical Point
受最近在YbRh $_2$ Si $_2$中的霍尔效应实验的启发,我们用变分蒙特卡罗方法研究了二维正方晶格中Kondo晶格模型的基态性质.我们发现了两种类型的相变:反铁磁相变和拓扑相变(费米面重构)。在很宽的参数范围内,这两个转变同时发生,而没有近藤屏蔽的崩溃,伴随着霍尔系数的不连续变化。这一结果与实验一致,并给出了重费米子系统量子临界点的一个新的理论图象。
Kondo scaling of $4f$-electron states and the Kondo singlet breakdown in heavy fermions
Helmholtz-Zentrum Berlin für Materialien und Energie(柏林亥姆霍兹材料与能源中心);Heidelberg University(海德堡大学);Synchrotron SOLEIL(SOLEIL同步辐射中心);Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes-UMR6226(雷恩大学,法国国家科学研究中心,雷恩化学科学研究所);Université de Lorraine, CNRS, Institut Jean Lamour(洛林大学,法国国家科学研究中心,让·拉穆尔研究所);National Synchrotron Radiation Research Center(国家同步辐射研究中心)
Quantum Monte Carlo studies of U(1) lattice gauge models of Kondo breakdown
Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg(维尔茨堡大学理论与天体物理研究所及维尔茨堡-德累斯顿ct.qmat卓越集群)
Breakdown of heavy quasiparticles in a honeycomb Kondo lattice: A quantum Monte Carlo study
我们表明,对于蜂窝晶格上的半填充近藤晶格模型,近藤击穿发生在磁有序相内的小近藤耦合$J_k$处。我们的结论是基于辅助场量子蒙特卡罗模拟的所谓的复合费米子谱函数。在近藤模型的U(1)规范理论表述中,很明显希格斯机制决定了谱函数中共振的权重。对于蜂窝晶格,我们观察到,对于小$J_k$的准粒子极点让位于不相干的光谱权重,但它仍然很好地定义为正方形晶格。我们的结果提供了一个明确的例子,其中重准粒子的磁跃迁和击穿分离,如在Yb(Rh $_{0.93}$ Co $_{0.07}$)$_2$ Si $_2$中观察到的[Friedemann等人,\textbf{5},465(2009)]。
Emergence of a symmetry-broken Chern insulator near a moiré Kondo breakdown
Shanghai Jiao Tong University(上海交通大学);Cornell University(康奈尔大学);Kavli Institute at Cornell for Nanoscale Science(康奈尔纳米科学卡弗里研究所);Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences(中国科学院物理研究所凝聚态物理国家实验室);Tsung-Dao Lee Institute, Shanghai Jiao Tong University(上海交通大学李政道研究所);National Institute for Materials Science(国立材料研究所);Hefei National Laboratory(合肥国家实验室);Max Planck Institute for the Structure and Dynamics of Matter(马克斯·普朗克物质结构动力学研究所)
Flat-Band Driven Kondo Breakdown and Reentrant Effects in Heavy-Fermion Moiré Superlattices
Institute of Software Technology, German Aerospace Center(德国航空航天中心软件技术研究所);Theoretical Division, Los Alamos National Laboratory(洛斯阿拉莫斯国家实验室理论部);Center for Integrated Nanotechnologies, Los Alamos National Laboratory(洛斯阿拉莫斯国家实验室集成纳米技术中心);Department of Physics, Condensed Matter Theory, TU Dortmund University(多特蒙德工业大学凝聚态理论物理系)
Kondo breakdown induced by non-Hermitian complex hybridization
Research Institute for Innovation and Co-Creation, Osaka Metropolitan University(大阪公立大学创新与共创研究所);Department of Physics, Osaka Metropolitan University(大阪公立大学物理系);Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), Osaka Metropolitan University(大阪公立大学南部阳一郎理论实验物理研究所);Department of Physics, Institute of Science Tokyo(东京科学大学物理系);Department of Physics, University of Tokyo(东京大学物理系);Fundamental Quantum Science Program, TRIP Headquarters, RIKEN(理化学研究所TRIP总部基础量子科学项目);Department of Physics, Ritsumeikan University(立命馆大学物理系);Department of Materials Engineering Science, University of Osaka(大阪大学材料工程科学系)
A Mean-Field Study of Quantum Oscillations in Two-Dimensional Kondo Insulators
Max Planck Institute for the Structure and Dynamics of Matter(马克斯·普朗克物质与结构动力学研究所);Department of Physics, University of Cincinnati(辛辛那提大学物理系);Department of Physics and Engineering Physics, Tulane University(杜兰大学物理与工程物理系)