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Kondo effect in double quantum dots with ferromagnetic RKKY interaction
Lei Pan1, YuanDong Wang, ZhenHua Li
1Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|November 15, 2016
Summary
We investigated the Kondo effect in double quantum dots with ferromagnetic interactions. Ferromagnetic coupling enhances the Kondo peak, leading to a
Area of Science:
- Condensed Matter Physics
- Quantum Dot Physics
Background:
- The Kondo effect describes the interaction between localized magnetic moments and conduction electrons in metals.
- Understanding quantum dot systems is crucial for developing advanced electronic devices.
Purpose of the Study:
- To investigate the Kondo effect in parallel-coupled double quantum dots with ferromagnetic Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction.
- To construct and analyze the phase diagram of this system.
Main Methods:
- Utilized the exact and nonperturbative hierarchical equations of motion approach.
- Constructed a phase diagram in the parameter plane of inter-dot coupling (t) and ferromagnetic exchange interaction (J).
Main Results:
- Identified three distinct ground states: Kondo singlet, spin singlet, and S=1 Kondo.
- Observed a 'J-enhanced Kondo effect' where ferromagnetic coupling raises the Kondo peak.
- Discovered a 't-enhanced Kondo effect' at J=0.
- Verified the ground state at large J as an under-screening Kondo state.
Conclusions:
- Ferromagnetic interactions significantly influence the Kondo effect in double quantum dots.
- The study reveals novel Kondo effect enhancements and identifies specific ground states.
- Results are consistent with the 'singular Fermi liquid state' described in existing literature.
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