Theory of Kondo Effect in Superconductors. I: Transition Temperature and Upper Critical Field

Matsuura, Tamifusa; Ichinose, S.; Nagaoka, Yosuke

doi:10.1143/ptp.57.713

Cited by 83 publications

(21 citation statements)

References 2 publications

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“…In agreement with ab initio calculations, this correlation is directly linked to the existence of an orbital occupation-dependent oscillatory behavior, with vanishing magnetic interactions for elements at the opposite extremes of the 3 d element series. Moreover, by driving the system in the normal metallic regime, we reveal the emergence of zero-bias anomalies which, in sharp contrast to expectations, become progressively stronger by approaching the quantum phase transition from the Kondo to the free-spin regime in the well-known phase diagram of magnetic impurities coupled to superconductors 29 . Supported by ab initio calculations based on density functional theory (DFT), relativistic time-dependent DFT (TD-DFT) 30 – 32 , and many-body perturbation theory (MBPT) 33 , 34 , these low-energy spectroscopic features are identified as unconventional spin excitations emerging from finite magnetic anisotropy energy.…”

Section: Introductioncontrasting

confidence: 63%

Correlating Josephson supercurrents and Shiba states in quantum spins unconventionally coupled to superconductors

et al. 2021

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Local spins coupled to superconductors give rise to several emerging phenomena directly linked to the competition between Cooper pair formation and magnetic exchange. These effects are generally scrutinized using a spectroscopic approach which relies on detecting the in-gap bound modes arising from Cooper pair breaking, the so-called Yu-Shiba-Rusinov (YSR) states. However, the impact of local magnetic impurities on the superconducting order parameter remains largely unexplored. Here, we use scanning Josephson spectroscopy to directly visualize the effect of magnetic perturbations on Cooper pair tunneling between superconducting electrodes at the atomic scale. By increasing the magnetic impurity orbital occupation by adding one electron at a time, we reveal the existence of a direct correlation between Josephson supercurrent suppression and YSR states. Moreover, in the metallic regime, we detect zero bias anomalies which break the existing framework based on competing Kondo and Cooper pair singlet formation mechanisms. Based on first-principle calculations, these results are rationalized in terms of unconventional spin-excitations induced by the finite magnetic anisotropy energy. Our findings have far reaching implications for phenomena that rely on the interplay between quantum spins and superconductivity.

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Section: Introductioncontrasting

confidence: 63%

Correlating Josephson supercurrents and Shiba states in quantum spins unconventionally coupled to superconductors

et al. 2021

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“…In 1960 Abrikosov and Gor'kov developed a theory of impurities in superconductors as pair breakers [14], which treated impurity scattering in the Born approximation and was therefore limited to weak coupling. Subsequently, attempts to incorporate the Kondo effect have been made by many authors [15][16][17][18][19]. Shiba [20] showed in an exactly solvable model of a classical impurity that there is a mid-gap excited bound state whose energy crosses zero as the interaction strength is varied.…”

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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“…where we have defined the ratio b = T K /T c0 in order to compare the Kondo scale with respect to T c0 -adopted as an scale of reference. Now for the sake of comparison with previous results in the literature [11,12] see Fig. 4 for T K ≤ T c0 (left panel) and T K ≥ T c0 (right panel).…”

Section: Kondo Effectmentioning

confidence: 57%

“…The dynamics of the model (2) governed by the equations of motion (12) and (13) can be reduced to the first order equations [7,8]…”

Section: Introductionmentioning

confidence: 99%

Kondo effect from a Lorentz-violating domain wall description of superconductivity

Bazeia¹,

Brito²,

Mota-Silva³

2016

Physics Letters B

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We extend recent results on domain wall description of superconductivity in an Abelian Higgs model by introducing a particular Lorentz-violating term. The temperature of the system is interpreted through the fact that the soliton following accelerating orbits is a Rindler observer experiencing a thermal bath. We show that this term can be associated with the Kondo effect, that is, the Lorentz-violating parameter is closely related to the concentration of magnetic impurities living on a superconducting domain wall. We also found that the critical temperature decreasing with the impurity concentration as a non single-valued function, for the case TK < Tc0, develops a negative curvature and presents deviations from the Abrikosov and Gor'kov theory, a phenomenon already supported by experimental evidence. * Electronic address:

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Theory of Kondo Effect in Superconductors. I: Transition Temperature and Upper Critical Field

Cited by 83 publications

References 2 publications

Correlating Josephson supercurrents and Shiba states in quantum spins unconventionally coupled to superconductors

Correlating Josephson supercurrents and Shiba states in quantum spins unconventionally coupled to superconductors

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

Kondo effect from a Lorentz-violating domain wall description of superconductivity

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