Two channel orbital Kondo effect in quantum dot with SO(n) symmetry

TL;DR

This paper proposes a model for a non-Fermi-liquid Kondo effect in a symmetric triple quantum dot system with SO(n) symmetry, revealing complex multistage renormalization and phase competition.

Contribution

It introduces a new scenario for symmetry-protected NFL Kondo effect in quantum dots with SO(n) symmetry and details the multistage renormalization process from SO(8) to SO(5).

Findings

Identification of NFL phase with swapped spin and orbital roles.

Multistage RG flow from SO(8) to SO(5).

Competition among three low-energy phases.

Abstract

A scenario for the formation of symmetry protected non-Fermi-liquid (NFL) Kondo effect (KE) with spin variable enumerating Kondo channels is suggested and worked out. In doubly occupied symmetric triple quantum dot within parallel geometry, the NFL low-energy regime arises provided the device possesses both source-drain and left-right parity. Kondo screening follows a multistage renormalization group mechanism: reduction of the energy scale is accompanied by the change of the relevant symmetry group from SO(8) to SO(5). At low energy, three phases compete: 1) under-screening spin triplet (conventional) KE; 2) spin singlet potential scattering; 3) NFL phase where the roles of spin and orbital degrees of freedom are swapped.