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arXiv · 1605.05803

SU(2)-SU(4) Kondo Crossover and Emergent Electric Polarization in a Triangular Triple Quantum Dot

Mikito Koga·Masashige Matsumoto·Hiroaki Kusunose
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Abstract

We study an orbitally degenerate Kondo effect in a triangular triple quantum dot (TTQD), where the three dots are connected vertically with a single metallic lead through electron tunneling. Both spin and orbital degrees of freedom play an important role in the SU(4) Kondo effect. This is demonstrated by an equilateral TTQD Kondo system at half-filling, by Wilson's numerical renormalization group method. We show how an emergent electric polarization of the TTQD is associated with a crossover from SU(4) to SU(2) symmetry in the low-temperature state. A marked sign reversal of the electric polarization is generated by the fine-tuning of Kondo coupling with degenerate orbitals, which can be utilized to reveal orbital dynamics in the SU(4) Kondo effect.

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Mikito Koga, Masashige Matsumoto, Hiroaki Kusunose. 2016-05-19. SU(2)-SU(4) Kondo Crossover and Emergent Electric Polarization in a Triangular Triple Quantum Dot. https://doi.org/10.7566/jpsj.85.063702

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