Local moment physics in heavy electron systems

Coleman, Piers

doi:10.1063/1.1509142

Cited by 19 publications

(23 citation statements)

References 72 publications

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“…A celebrated example is the Kondo effect [3] signified by the increase of electrical resistance of alloys with dilute magnetic impurities as decreasing temperature. The problem of clarifying the whole crossover of an impurity spin from a doublet state at high temperature to a singlet state at low temperature in the case of antiferromagnetic coupling between the impurity and conduction electrons, has defied a straightforward perturbative solution and prompted the development of a variety of nonperturbative techniques, e.g., Anderson's poor man's scaling [4], the large-N slave boson approach [5,6], and Wilson's numerical renormalization group (NRG) [7], all of which have made a substantial contribution to the foundation of a modern theoretical framework for heavy fermion systems [7][8][9][10][11]. In recent years, interests in the Kondo effect were refueled by advances in nanotechnology and new discoveries continue to be made [12].…”

Section: Introductionmentioning

confidence: 99%

Overscreened Kondo effect, (color) superconductivity, and Shiba states in Dirac metals and quark matter

Kanazawa

Uchino

2016

Phys. Rev. D

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We study the interplay between the Kondo effect and (color) superconductivity in doped Dirac metals with magnetic impurities and in quark matter with colorful impurities. We first point out that the overscreened Kondo effect arises in the normal state of these systems. Next the (color) superconducting gap is incorporated as a mean field and the phase diagram for a varying gap and temperature is constructed nonperturbatively. A rich phase structure emerges from a competition of effects unique to a multichannel system. The Kondo-screened phase is shown to disappear for a sufficiently large gap. Peculiarity of quark matter due to the confining property of non-Abelian gauge fields is noted. We also investigate the spectrum of sub-gap excited states, called Shiba states. Based on a model calculation and physical reasoning we predict that, as the coupling of the impurity to the bulk is increased, there will be more than one quantum phase transition due to level crossing among overscreened states.

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Section: Introductionmentioning

confidence: 99%

Overscreened Kondo effect, (color) superconductivity, and Shiba states in Dirac metals and quark matter

Kanazawa

Uchino

2016

Phys. Rev. D

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“…Magnetic impurities have dramatic effects in transport properties known as Kondo effect [49,50,51,52,53,54,55]. The Kondo effect in the helical edge states of the 2D topological insulators is an important question both theoretical and experimental.…”

Section: Kondo Problem In the Helical Edge Modesmentioning

confidence: 99%

Novel Quantum States with Exotic Spin Properties - Unconventional Generalization of Magnetism

Li¹,

Hung²,

Cai³

et al. 2011

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. My group has investigated the unconventional meta-magnetic states in the Sr3Ru2O7 system, topological insulators, and superconductivity in iron-based superconductors. First, we constructed the microscopic mechanism of the nematic states in the Sr3Ru2O7 system based on its quasi-one-dimensional band structure. The calculated phase diagram agrees with the experimental observation. We performed the detailed theoretical analysis of the quasi-particle interference (QPI) spectroscopy of the STM measurement, which is in nice agreement with the Novel quantum states with exotic spin properties--Unconventional generalization of magnetism Report Title ABSTRACTMy group has investigated the unconventional meta-magnetic states in the Sr3Ru2O7 system, topological insulators, and superconductivity in iron-based superconductors. First, we constructed the microscopic mechanism of the nematic states in the Sr3Ru2O7 system based on its quasi-one-dimensional band structure. The calculated phase diagram agrees with the experimental observation. We performed the detailed theoretical analysis of the quasi-particle interference (QPI) spectroscopy of the STM measurement, which is in nice agreement with the experimental results. Second, we studied strong correlation effects in the 2D topological insulators by performing the sign-problem-free quantum Monte-Carlo simulations, and obtained the phase diagram. How the edge states are destabilized at an intermediate interaction strength is investigated. We have also constructed models of 3D topological insulators based on the generalization of Landau levels. The elegant analytical properties of Landau level provides a good starting point for the future study of fractional topological insulators in 3D. Third, we have investigated the unconventional superconductivity in iron-based superconductors. Time-reversal symmetry breaking states are proposed and the experimentally testable signatures are presented. We further provided a theory explanation of the anisotropic states observed in FeSe superconductors based on orbital ordering.

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“…A common aspect of such compounds is the formation of quasiparticle bands with extremely large effective masses (and hence large values of the low-temperature specific heat coefficient γ = C/T ), up to a thousand time the bare electron mass ! Hence the term "heavy-fermion" given to these compounds: for reviews, see e.g [22,23]. The origin of these large effective masses is the weak hybridization between the very localised f-orbitals and the rather broad conduction band associated with the metallic ion.…”

Section: F-electrons: Rare Earths Actinides and Their Compoundsmentioning

confidence: 99%

Strongly Correlated Electron Materials: Dynamical Mean-Field Theory and Electronic Structure

Georges¹

2004

AIP Conference Proceedings

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Abstract. These are introductory lectures to some aspects of the physics of strongly correlated electron systems. I first explain the main reasons for strong correlations in several classes of materials. The basic principles of dynamical mean-field theory (DMFT) are then briefly reviewed. I emphasize the formal analogies with classical mean-field theory and density functional theory, through the construction of free-energy functionals of a local observable. I review the application of DMFT to the Mott transition, and compare to recent spectroscopy and transport experiments. The key role of the quasiparticle coherence scale, and of transfers of spectral weight between low-and intermediate or high energies is emphasized. Above this scale, correlated metals enter an incoherent regime with unusual transport properties. The recent combinations of DMFT with electronic structure methods are also discussed, and illustrated by some applications to transition metal oxides and f-electron materials.

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Local moment physics in heavy electron systems

Cited by 19 publications

References 72 publications

Overscreened Kondo effect, (color) superconductivity, and Shiba states in Dirac metals and quark matter

Overscreened Kondo effect, (color) superconductivity, and Shiba states in Dirac metals and quark matter

Novel Quantum States with Exotic Spin Properties - Unconventional Generalization of Magnetism

Strongly Correlated Electron Materials: Dynamical Mean-Field Theory and Electronic Structure

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