Kondo effect
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Emergence of Kondo lattice behavior in a van der Waals itinerant ferromagnet, Fe <sub>3</sub> GeTe <sub>2</sub> Open
Ferromagnetism and the Kondo effect are crucial for 3d electrons to become spin-separated and heavy at the same time.
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Non-Hermitian Kondo Effect in Ultracold Alkaline-Earth Atoms Open
We investigate the Kondo effect in an open quantum system, motivated by recent experiments with ultracold alkaline-earth(-like) atoms. Because of inelastic collisions and the associated atom losses, this system is described by a complex-va…
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Weyl–Kondo semimetal in heavy-fermion systems Open
Significance While electronic states with nontrivial topology have traditionally been known in insulators, they have been evidenced in metals during the past 2 years. Such Weyl semimetals show topological protection while conducting electr…
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Tunable quantum criticality and super-ballistic transport in a “charge” Kondo circuit Open
A nanostructure quantum simulator Phase transitions occurring at absolute zero temperature, or quantum phase transitions (QPTs), can be grouped into broad categories called universality classes. The classification is based on the propertie…
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Giant spontaneous Hall effect in a nonmagnetic Weyl–Kondo semimetal Open
Significance States of matter are traditionally classified by their symmetry, as exemplified by the distinction between a solid and a liquid. Topological quantum phases, on the other hand, are harder to characterize, and still harder to id…
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Kondo Insulator to Semimetal Transformation Tuned by Spin-Orbit Coupling Open
Recent theoretical studies of topologically nontrivial electronic states in Kondo insulators have pointed to the importance of spin-orbit coupling (SOC) for stabilizing these states. However, systematic experimental studies that tune the S…
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Thermoelectricity in correlated narrow-gap semiconductors Open
We review many-body effects, their microscopic origin, as well as their impact on thermoelectricity in correlated narrow-gap semiconductors. Members of this class-such as FeSi and FeSb2-display an unusual temperature dependence in various …
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The Anderson–Josephson quantum dot—a theory perspective Open
Recent progress in nanoscale manufacturing has allowed to experimentally investigate quantum dots coupled to two superconducting leads in controlled and tunable setups. The equilibrium Josephson current was measured in on-chip superconduct…
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Entropy Evolution in the Magnetic Phases of Partially Frustrated CePdAl Open
In the heavy-fermion metal CePdAl, long-range antiferromagnetic order coexists with geometric frustration of one-third of the Ce moments. At low temperatures, the Kondo effect tends to screen the frustrated moments. We use magnetic fields …
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Direct Probe of the Seebeck Coefficient in a Kondo-Correlated Single-Quantum-Dot Transistor Open
We report on the first measurement of the Seebeck coefficient in a tunnel-contacted and gate-tunable individual single-quantum dot junction in the Kondo regime, fabricated using the electromigration technique. This fundamental thermoelectr…
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Fingerprints of the Local Moment Formation and its Kondo Screening in the Generalized Susceptibilities of Many-Electron Problems Open
We identify the precise hallmarks of the local magnetic moment formation and its Kondo screening in the frequency structure of the generalized charge susceptibility. The sharpness of our identification even pinpoints an alternative criteri…
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Samarium hexaboride is a trivial surface conductor Open
SmB6 is predicted to be the first member of the intersection of topological insulators and Kondo insulators, strongly correlated materials in which the Fermi level lies in the gap of a many-body resonance that forms by hybridization betwee…
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Thermoelectric Characterization of the Kondo Resonance in Nanowire Quantum Dots Open
We experimentally verify hitherto untested theoretical predictions about the thermoelectric properties of Kondo correlated quantum dots (QDs). The specific conditions required for this study are obtained by using QDs epitaxially grown in n…
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Proximity-Induced Shiba States in a Molecular Junction Open
Superconductors containing magnetic impurities exhibit intriguing phenomena derived from the competition between Cooper pairing and Kondo screening. At the heart of this competition are the Yu-Shiba-Rusinov (Shiba) states which arise from …
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Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms Open
We propose a scheme to realize the Kondo model with tunable anisotropy using alkaline-earth atoms in an optical lattice. The new feature of our setup is Floquet engineering of interactions using time-dependent Zeeman shifts, that can be re…
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Kondo effect in alkaline-earth-metal atomic gases with confinement-induced resonances Open
Alkali-earth atoms have a long-lived electronic excited state, which can be\nlocalized in the Fermi sea of ground state atoms by an external potential and\nserve as magnetic impurities, due to the spin-exchange interaction between the\nexc…
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Fermi surfaces in Kondo insulators Open
We report magnetic quantum oscillations measured using torque magnetisation in the Kondo insulator YbB12 and discuss the potential origin of the underlying Fermi surface. Observed quantum oscillations as well as complementary quantities su…
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Fractional Entropy of Multichannel Kondo Systems from Conductance-Charge Relations Open
Fractional entropy is a signature of nonlocal degrees of freedom, such as Majorana zero modes or more exotic non-Abelian anyons. Although direct experimental measurements remain challenging, Maxwell relations provide an indirect route to t…
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Solving Quantum Impurity Problems in and out of Equilibrium with the Variational Approach Open
A versatile and efficient variational approach is developed to solve in- and\nout-of-equilibrium problems of generic quantum spin-impurity systems. Employing\nthe discrete symmetry hidden in spin-impurity models, we present a new\ncanonica…
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Interleaved numerical renormalization group as an efficient multiband impurity solver Open
Quantum impurity problems can be solved using the numerical renormalization\ngroup (NRG), which involves discretizing the free conduction electron system\nand mapping to a `Wilson chain'. It was shown recently that Wilson chains for\ndiffe…
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Kondo blockade due to quantum interference in single-molecule junctions Open
Molecular electronics offers unique scientific and technological possibilities, resulting from both the nanometre scale of the devices and their reproducible chemical complexity. Two fundamental yet different effects, with no classical ana…
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Dynamics of Kondo voltage splitting after a quantum quench Open
We analyze the time-dependent formation of the spectral function of an\nAnderson impurity model in the Kondo regime within a numerically exact\nreal-time quantum Monte Carlo framework. At steady state, splitting of the\nKondo peak occurs w…
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Topological surface states interacting with bulk excitations in the Kondo insulator SmB <sub>6</sub> revealed via planar tunneling spectroscopy Open
Significance Topological insulators are an emerging class of quantum matter in which the nontrivial bulk band structure gives rise to topologically protected surface states. Most are weakly correlated band insulators such as Bi 2 Se 3 . De…
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Universality and Scaling in a Charge Two-Channel Kondo Device Open
We study a charge two-channel Kondo model, demonstrating that recent experiments [Z. Iftikhar et al, Nature (London) 526, 233 (2015)] realize an essentially perfect quantum simulation-not just of its universal physics, but also nonuniversa…
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Kondo physics in antiferromagnetic Weyl semimetal Mn <sub> 3+ <i>x</i> </sub> Sn <sub> 1− <i>x</i> </sub> films Open
Evolution of Kondo effect in Weyl semimetal Mn 3 Sn leads to extraordinary terahertz and DC transport properties.
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Model for a Ferromagnetic Quantum Critical Point in a 1D Kondo Lattice Open
Motivated by recent experiments, we study a quasi-one-dimensional model of a Kondo lattice with ferromagnetic coupling between the spins. Using bosonization and dynamical large-N techniques, we establish the presence of a Fermi liquid and …
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Entanglement structure of the two-channel Kondo model Open
Two electronic channels competing to screen a single impurity spin, as in the\ntwo-channel Kondo model, are expected to generate a ground state with\nnontrivial entanglement structure. We exploit a spin-chain representation of\nthe two-cha…
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Yu-Shiba-Rusinov states in real metals Open
Theoretical descriptions of Yu-Shiba-Rusinov (YSR) states induced by magnetic impurities inside the gap of a superconductor typically rely on a classical spin model or are restricted to spin-12 quantum spins. These models fail to account f…
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Gate-tunable heavy fermion quantum criticality in a moiré Kondo lattice Open
We propose a realization of Kondo lattice physics in moiré superlattices at the interface between a WX2 homobilayer and MoX2 monolayer (X = S,Se). Under appropriate gating conditions, the interface WX2 layer forms a triangular lattice of l…
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Observation of tunable single-atom Yu-Shiba-Rusinov states Open
The coupling of a spin to an underlying substrate is the basis for a plethora\nof phenomena. In the case of a metallic substrate, Kondo screening of the\nadatom magnetic moment can occur. As the substrate turns superconducting, an\nintrigu…