We study the low-temperature properties of a one-dimensional spin-1/2 chain of magnetic impurities coupled to a (normal) metal environment by means of anisotropic Kondo exchange. In the case of easy-plane anisotropy, we obtain the phase diagram of this system at T=0. We show that the in-plane Kondo coupling destabilizes the Tomonaga-Luttinger phase of the spin-chain, and leads to two different phases: i) At strong Kondo coupling, the spins in the chain form Kondo singlets and become screened by the metallic environment, and ii) At weak and intermediate Kondo coupling, we find a novel dissipative phase characterized by diffusive gapless spin excitations. The two phases are separated by a quantum critical point of the Wilson-Fisher universality class with dynamical exponent $z\simeq2$.
The effective Kondo model for a trimer on a metallic surface
我考虑了一个Hubbard-Anderson模型，它描述了三个不同原子的局域轨道，它们之间的杂交和连续的扩展状态（ES）。利用推广的Schriffl-Wolf变换，导出了孤立三聚体的双重态基态与ES相互作用的有效Kondo模型。对于原子间距离为a，l，l的等腰三聚体，当a较小时，近藤温度对l a可< a and has a maximum for finite l >忽略不计。结果与Au（111）上Cr三聚体的实验结果一致。[T. Jamneala等人，物理修订信函87，256804（2001）]。
We apply our recently developed, selfconsistent renormalization group (RG) method to STM spectra of a two-impurity Kondo system consisting of two cobalt atoms connected by a one-dimensional Cu chain on a Cu surface. This RG method was developed to describe local spin screening in multi-impurity Kondo systems in presence of the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. Using the RKKY interaction of a one-dimensional chain, we explain the experimentally observed suppression and oscillation of the Kondo temperature, $T_K(y)$, as a function of the length of the chain and the corresponding …
We explore the physics of a spin-1/2 Heisenberg chain with Kondo interaction, $J_k$, to a two-dimensional electron gas. At weak $J_k$ the problem maps onto a Heisenberg chain locally coupled to a dissipative Ohmic bath. At the decoupled fixed point, the dissipation is a marginally relevant perturbation and drives long-range antiferromagnetic order along the chain. In the dynamical spin structure factor we observe a quadratic low-energy dispersion akin to Landau-damped Goldstone modes. At large $J_k$ Kondo screening dominates, and the spin correlations of the chain inherit the power law of the …
We study surface state plasmonics in the periodic Anderson model of a bulk topological Kondo insulator system, involving strongly correlated f electrons screened by weakly correlated d electrons, performing a mean-field theoretic calculation within the frame-work of slave-boson protocol. We include the effect of magnetic impurities as well which do not act as scattering agent in our scheme; the exchange interaction due to them is included in the band dispersion. The interaction opens a gap at the surface states with gapless Dirac dispersion. We find that bulk insulation together with the surfa…
Magnetic frustrations can enhance quantum zero-point motion in spin systems and lead to exotic topological insulating states. When coupled to mobile electrons, they may lead to unusual non-Fermi liquid or metallic spin liquid states whose nature has not been well explored. Here, we propose a spin current Kondo mechanism underlying a series of non-Fermi liquid phases on the border of Kondo and magnetic phases in a frustrated three-impurity Kondo model. This mechanism is confirmed by renormalization group analysis and describes movable Kondo singlets called "holons" induced by an effective coupl…
Topological-Mass Control of an Emergent Kondo Scale in an Interacting SSH Chain
Center for Liberal Arts and Sciences, Sanyo-Onoda City University（山阳小野田市立大学通识教育中心）；Department of Engineering, Sanyo-Onoda City University（山阳小野田市立大学工程系）
How many magnetic moments periodically arranged on a metallic surface are needed to generate a coherent Kondo lattice behavior? We investigate this fundamental issue within the particle-hole symmetric Kondo lattice model using quantum Monte Carlo simulations. Extra magnetic atoms forming closed shells around the initial impurity induce a fast splitting of the Kondo resonance at the inner shells which signals the formation of composite heavy-fermion bands. The onset of the hybridization gap matches well the enhancement of antiferromagnetic spin correlations in the plane perpendicular to the app…
Artificially built Kondo chains with organic radicals on metallic surfaces: new model system of heavy fermion quantum criticality
The Hong Kong University of Science and Technology（香港科技大学）；Universität Würzburg（维尔茨堡大学）；Shanghai Jiao Tong University（上海交通大学）；The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen)（香港中文大学（深圳））；Hefei National Laboratory（合肥国家实验室）
We study a generic topological Kondo insulator system by performing a mean-field theoretic calculation within the frame-work of slave-boson protocol. We assume infinite Hubbard-type interaction among the localized electrons. The difference between the bulk metallic and insulating phases of the insulator is in the sign of nearest neighbor hopping of localized electrons. The hopping amplitude is positive for the metallic and negative for the insulating phase. The surface metallicity together with bulk insulation, however, requires very strong f electron localization. Furthermore, we find that th…
We study the Kondo chain in the regime of high spin concentration where the low energy physics is dominated by the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. As has been recently shown (A. M. Tsvelik and O. M. Yevtushenko, Phys. Rev. Lett 115, 216402 (2015)), this model has two phases with drastically different transport properties depending on the anisotropy of the exchange interaction. In particular, the helical symmetry of the fermions is spontaneously broken when the anisotropy is of the easy plane type (EP). This leads to a parametrical suppression of the localization effects. In t…
Combining ab initio calculations and effective models derived from them, we discuss the electronic structure of oxygen doped gold chains when one Au atom is replaced by any transition-metal atom of the $3d$ series. The effect of O doping is to bring extended Au $5d_{xz}$ and $5d_{yz}$ states to the Fermi level, which together with the Au states of zero angular momentum projection, lead to three possible channels for the screening of the magnetism of the impurity. For most 3d impurities the expected physics is similar to that of the underscreened Kondo model, with singular Fermi liquid behavior…
Motivated by the fact that the low-energy properties of the Kondo model can be effectively simulated in spin chains, we study the realization of the effect with bond impurities in ultracold bosonic lattices at half-filling. After presenting a discussion of the effective theory and of the mapping of the bosonic chain onto a lattice spin Hamiltonian, we provide estimates for the Kondo length as a function of the parameters of the bosonic model. We point out that the Kondo length can be extracted from the integrated real space correlation functions, which are experimentally accessible quantities …
Low temperature dephasing in irradiated metallic wires
我们提出了相位相干时间测量准一维银线注入银$^{+}$离子的能量为$100 keV$。测量已进行的温度范围从$100 mK$到$10 K$ ;这必须与近藤温度的铁在银，即$T_{K}^{Ag/Fe} \approx 4 K$，在最近的实验中使用的近藤系统\cite{mallet_prl_06,birge_prl_06}的移相。我们发现，相位相干时间不受注入过程的影响，清楚地证明了离子注入过程本身\emph{does not lead to any extra dephasing}在低温下。
