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Local quantum critical behavior in magnetic Kondo impurity models with partially screened moment

Guang-Ming Zhang·Lu Yu
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Abstract

In the strong coupling limit, an effective resonant level model is derived for the spin-1 underscreened Kondo impurity model. A local quantum critical behavior is induced by the formation of a bound state with partially screened magnetic moment, displaying a residual $Z_2$ symmetry, leading to a $δ$-resonance at the Fermi level in the impurity spectral function. As a consequence, a logarithmic singularity appears in the real part of the impurity dynamic spin susceptibility as a function of $\max (ω, T)$, with $ω$ as frequency, $T$ temperature. A small magnetic field breaks this $Z_2$ symmetry and suppresses the singularity. We also discuss the possible manifestation of such a quantum critical behavior in the spin-1/2 two Kondo impurity model and the single quantum dot system with even electron occupation.

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Guang-Ming Zhang, Lu Yu. 2005-03-24. Local quantum critical behavior in magnetic Kondo impurity models with partially screened moment. https://arxiv.org/abs/cond-mat/0412561

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