Orbital Kondo effect modulated by off-diagonal orbital interference

TL;DR

This paper theoretically investigates how off-diagonal orbital interference and magnetic flux modulate the orbital Kondo effect in an Aharonov-Bohm interferometer, revealing flux-dependent Kondo temperature and conductance behaviors.

Contribution

It provides a detailed analysis of the flux-tunable orbital Kondo effect and derives an analytic expression for the flux-dependent Kondo temperature.

Findings

Kondo effect can be tuned by magnetic flux.

Off-diagonal interference modifies Kondo peak height and width.

Kondo temperature decreases with increasing flux.

Abstract

We report the theoretical investigation of the orbital Kondo effect in an Aharonov-Bohm interferometer by slave-boson mean field approach. It is found that the present orbital Kondo effect can be tuned geometrically by the external magnetic flux. When the magnetic flux $\phi =(2n+1)\pi $, the off-diagonal self-energy vanishes and the orbital Kondo problem can be exactly mapped onto the usual spin Kondo model. For a general $\phi $, the presence of the off-diagonal orbital wave function interference will modify the height and width of the orbital Kondo peak, but not change the position of the orbital Kondo peak. We also give an analytic expression of the flux-dependent Kondo temperature and find it decreases monotonously as the magnetic flux $\phi $ goes from $(2n+1)\pi $ to $2n\pi $, which means the Kondo effect is suppressed by the off-diagonal orbital interference process and becomes more easily destroyed by the thermal fluctuation. The flux-dependence conductance is also presented.