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Kondo decoherence: finding the right spin model for iron impurities in gold and silver
T A Costi1, L Bergqvist, A Weichselbaum
1Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany.
Physical Review Letters
|March 5, 2009
Summary
This study resolves the Kondo model for iron impurities in gold and silver by determining the spin value (S=3/2) using electron decoherence and resistivity measurements, confirming theoretical calculations.
Area of Science:
- Condensed Matter Physics
- Quantum Mechanics
- Materials Science
Background:
- The Kondo system describes interactions between magnetic impurities and conduction electrons.
- Previous studies on iron impurities in noble metals suggested a Kondo model but left the spin value ambiguous.
- Understanding the correct model is crucial for describing electron spin and orbital dynamics.
Purpose of the Study:
- To resolve the ambiguity in the spin value (S) for the Kondo model of iron impurities in gold and silver.
- To determine which Kondo-type model accurately describes the electronic properties, including multiple bands and spin/orbital degrees of freedom.
Main Methods:
- Utilizing electron decoherence, studied via weak localization, as a probe for magnetic impurities.
- Performing density functional theory (DFT) calculations to predict the spin value.
- Comparing experimental measurements (resistivity and decoherence rate) with numerical renormalization group (NRG) predictions.
Main Results:
- Density functional theory calculations suggest a spin value of S=3/2 for iron impurities.
- Experimental measurements of resistivity and decoherence rate in quasi-one-dimensional wires show excellent agreement with NRG predictions for S=3/2.
- This confirms the S=3/2 Kondo model as a realistic description.
Conclusions:
- The long-standing question regarding the Kondo model for Fe impurities in Au and Ag is resolved.
- The study confirms S=3/2 as the correct spin value for these systems.
- This finding provides a more accurate understanding of electron behavior in these magnetic impurity systems.
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