Orbital Kondo behavior from dynamical structural defects

TL;DR

This paper investigates the orbital Kondo effect arising from dynamical structural defects modeled as atoms in double-well potentials, using renormalization group methods to compute the Kondo temperature and analyze its dependence on system parameters.

Contribution

The study provides a detailed renormalization group analysis of the orbital Kondo effect with multiple excited states, highlighting conditions for Kondo temperature proximity to 1 K and its relation to energy splitting.

Findings

Kondo temperature can approach 1 K for specific parameters

Kondo temperature generally remains below the energy splitting

Splitting remains unrenormalized above Debye frequency

Abstract

The interaction between an atom moving in a model double-well potential and the conduction electrons is treated using renormalization group methods in next-to-leading logarithmic order. A large number of excited states is taken into account and the Kondo temperature $T_K$ is computed as a function of barrier parameters. We find that for special parameters $T_K$ can be close to $1 {\rm K}$ and it can be of the same order of magnitude as the renormalized splitting $\Delta$. However, in the perturbative regime we always find that $T_K \alt \Delta $ with a $T_K \alt 1 {\rm K}$ [Aleiner {\em et al.}, Phys. Rev. Lett. {\bf 86}, 2629 (2001)]. We also find that $\Delta$ remains unrenormalized at energies above the Debye frequency, $\omega_{\rm Debye}$.