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Local moment formation and Kondo screening in impurity trimers
Andrew K Mitchell1, Thomas F Jarrold, Martin R Galpin
1Department of Chemistry, Physical and Theoretical Chemistry, Oxford University , South Parks Road, Oxford OX1 3QZ, United Kingdom.
The Journal of Physical Chemistry. B
|March 27, 2013
Summary
We theoretically studied a frustrated magnetic impurity trimer. Local frustration drives quantum phase transitions between Kondo-screened and local moment phases, relevant for quantum dot devices.
Area of Science:
- Condensed Matter Physics
- Quantum Chemistry
- Materials Science
Background:
- Frustration is a key feature in complex molecular systems where competing interactions occur.
- Magnetic impurity clusters offer a simplified model for studying frustration and its effects.
- Understanding impurity interactions is crucial for developing advanced electronic devices.
Purpose of the Study:
- To theoretically investigate a triangular cluster of three magnetic impurities interacting with conduction electrons.
- To explore the role of frustration in driving quantum phase transitions.
- To analyze the impact of orbital structure on Kondo screening and local moment formation.
Main Methods:
- Analytical arguments
- Numerical renormalization group (NRG) calculations
Main Results:
- Identified low-energy doublet states favored by effective exchange interactions due to strong electronic repulsion.
- Demonstrated parity symmetry protecting level crossings and avoided crossings in distorted cases.
- Observed quantum phase transitions between Kondo-screened Fermi liquid and local moment phases, driven by local frustration.
- Uncovered unusual mechanisms for local moment formation and Kondo screening arising from the impurity trimer's orbital structure.
Conclusions:
- The study provides a theoretical framework for understanding quantum phase transitions in frustrated magnetic systems.
- Results are relevant for the design and understanding of triple quantum dot devices.
- The interplay between local frustration and collective quantum many-body effects leads to rich physical phenomena.
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