Quantum critical points of an anisotropic multichannel Kondo impurity

Schlottmann, P.

doi:10.1063/1.1357846

Cited by 5 publications

(9 citation statements)

References 34 publications

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“…Thus for h = 0, a non-integer rest-spin remains in the case γ = 0, l > m and h-dependent corrections are of non-integer powers of h. The constant terms in (43) agree precisely with the asymptotes, equations ( 15) and with 8,9 , where the same model was investigated by TBAtechniques in the limits indicated in (43).…”

Section: Ground Statesupporting

confidence: 59%

“…We analysed the ground state for arbitrary anisotropy, spin and channel number and observed non-commutativity of the limits h, T → 0 for models with l = m. In the underscreened case, if h = 0, an asymptotic approach to free (l − m)/2 spin asymptotes was recovered for T ≪ T K , formally analogous to the T ≫ T K case, paragraph 4.2. On the other hand, performing first the limit T → 0 while letting h = 0, a non-integer rest spin occurs for γ = 0 in the underscreened case, equation (43), connected to a quantum critical point 8,9 .…”

Section: Resultsmentioning

confidence: 99%

“…Our claim, however, that (10)-(13), (14) hold also in the general case follows by a simpler reasoning. By use of the algebra 15,17 of fused transfer matrices one can show that our key equations are equivalent to the infinitely many TBA equations of 6 in the isotropic case and to the equations of 8,9 in the anisotropic case. As an illustration, figures 1-6 show the entropy and specific heat for some special cases.…”

Section: Calculation Of the Free Energymentioning

confidence: 98%

“…In the TBA approach, the free energy is encoded by infinitely many coupled non-linear integral equations. Recently, Schlottmann 8,9 and Zaránd et al 10 obtained the free energy for the anisotropic multichannel spin-S Kondo model with XXZ-like exchange in the TBA approach. Schlottmann observed a quantum critical point for the overscreened model in the limit of low temperatures, Zaránd et al focused on the underscreened twochannel model.…”

Section: Introductionmentioning

confidence: 99%

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The anisotropic multichannel spin-$\mathsf{S}$ Kondo model: Calculation of scales from a novel exact solution

Bortz

Klümper

2004

Eur. Phys. J. B

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A novel exact solution of the multichannel spin-S Kondo model is presented, based on a lattice path integral approach of the single channel spin-1/2 case. The spin exchange between the localized moment and the host is of XXZ-type, including the isotropic XXX limit. The free energy is given by a finite set of non-linear integral equations, which allow for an accurate determination of highand low-temperature scales.

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Section: Ground Statesupporting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Calculation Of the Free Energymentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The anisotropic multichannel spin-$\mathsf{S}$ Kondo model: Calculation of scales from a novel exact solution

Bortz

Klümper

2004

Eur. Phys. J. B

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“…35,36 The anisotropic Kondo model with D 0 ͑and with additional anisotropy in the exchange coupling͒ was studied by the Bethe-Ansatz technique. 47,48 It was shown that anisotropy can induce a quantum critical point ͑i.e., non-Fermiliquid behavior͒. The applicability of the Bethe-Ansatz approach is, however, limited to a set of models with restrained parameters; thus, a direct comparison with the model considered in this work is not possible.…”

Section: Modelmentioning

confidence: 99%

Properties of anisotropic magnetic impurities on surfaces

2008

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Using numerical renormalization group techniques, we study static and dynamic properties of a family of single-channel Kondo impurity models with axial magnetic anisotropy $DS_z^2$ terms; such models are appropriate to describe magnetic impurity atoms adsorbed on non-magnetic surfaces, which may exhibit surface Kondo effect. We show that for positive anisotropy $D$ and for any spin $S$, the systems behave at low temperatures as regular Fermi liquids with fully compensated impurity spin. The approach to the stable fixed point depends on the value of the spin $S$ and on the ratio $D/T_K^{(0)}$, where $T_K^{(0)}$ is the Kondo temperature in the absence of the anisotropy. For S=1, the screening occurs in two stages if $DT_K^{(0)}$. For negative anisotropy $D$, the system is a non-Fermi liquid with residual anisotropic exchange interaction. However, the presence of transverse magnetic anisotropy $E(S_x^2-S_y^2)$ restores Fermi-liquid behavior in real systems.Comment: 14 pages, 12 figure

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c-axis magnetotransport inCeCoIn5

et al. 2005

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We present the results of out-of-plane electrical transport measurements on the heavy fermion superconductor CeCoIn5 at temperatures from 40 mK to 400 K and in magnetic field up to 9 T. For T < 10 K transport measurements show that the zero-field resistivity ρc changes linearly with temperature and extrapolates nearly to zero at 0 K, indicative of non-Fermi-liquid (nFL) behavior associated with a quantum critical point (QCP). The longitudinal magnetoresistance (LMR) of CeCoIn5 for fields applied parallel to the c-axis is negative and scales as B/(T + T * ) between 50 and 100 K, revealing the presence of a single-impurity Kondo energy scale T * ∼ 2 K. Beginning at 16 K a small positive LMR feature is evident for fields less than 3 tesla that grows in magnitude with decreasing temperature. For higher fields the LMR is negative and increases in magnitude with decreasing temperature. This sizable negative magnetoresistance scales as B 2 /T from 2.6 K to roughly 8 K, and it arises from an extrapolated residual resistivity that becomes negative and grows quadratically with field in the nFL temperature regime. Applying a magnetic field along the c-axis with B > Bc2 restores Fermi-liquid behavior in ρc(T ) at T less than 130 mK. Analysis of the T 2 resistivity coefficient's field-dependence suggests that the QCP in CeCoIn5 is located below the upper critical field, inside the superconducting phase. These data indicate that while high-T c-axis transport of CeCoIn5 exhibits features typical for a heavy fermion system, low-T transport is governed both by spin fluctuations associated with the QCP and Kondo interactions that are influenced by the underlying complex electronic structure intrinsic to the anisotropic CeCoIn5 crystal structure.

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Quantum critical points of an anisotropic multichannel Kondo impurity

Cited by 5 publications

References 34 publications

The anisotropic multichannel spin-$\mathsf{S}$ Kondo model: Calculation of scales from a novel exact solution

The anisotropic multichannel spin-$\mathsf{S}$ Kondo model: Calculation of scales from a novel exact solution

Properties of anisotropic magnetic impurities on surfaces

c-axis magnetotransport inCeCoIn5

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