Iron impurities in gold and silver: Comparison of transport measurements to numerical renormalization group calculations exploiting non-Abelian symmetries

TL;DR

This paper improves numerical calculations of Kondo impurity effects in gold and silver by using non-Abelian symmetries, and confirms the spin-3/2 three-channel Kondo model as an accurate description of iron impurities through comparison with experimental data.

Contribution

It introduces enhanced NRG calculations exploiting non-Abelian symmetries and validates the spin-3/2 three-channel Kondo model against experimental resistivity and magnetoresistivity data.

Findings

Improved numerical data using non-Abelian symmetries.

Excellent agreement between theory and experiment for spin-3/2 model.

Validation of the three-channel Kondo model for iron impurities.

Abstract

We consider iron impurities in the noble metals gold and silver and compare experimental data for the resistivity and decoherence rate to numerical renormalization group results. By exploiting non-Abelian symmetries we show improved numerical data for both quantities as compared to previous calculations [Costi et al., Phys. Rev. Lett. 102, 056802 (2009)], using the discarded weight as criterion to reliably judge the quality of convergence of the numerical data. In addition we also carry out finite-temperature calculations for the magnetoresistivity of fully screened Kondo models with S = 1/2, 1 and 3/2, and compare the results with available measurements for iron in silver, finding excellent agreement between theory and experiment for the spin-3/2 three-channel Kondo model. This lends additional support to the conclusion of Costi et al. that the latter model provides a good effective description of the Kondo physics of iron impurities in gold and silver.