Majorana coupling and Kondo screening of localized spins

TL;DR

This paper investigates how Majorana modes influence the magnetic properties of a quantum dot, revealing a reduction in magnetic moment and an enhancement of the Kondo effect due to Majorana coupling.

Contribution

It provides a theoretical analysis combining analytical and numerical methods to show how Majorana modes affect magnetic moments and Kondo screening in quantum dot systems.

Findings

Majorana modes reduce the magnetic moment from 1/4 to 1/16.

Coupling to Majorana modes increases the Kondo temperature.

Kondo screening fully occurs below the Kondo temperature.

Abstract

We perform a theoretical analysis of the fate of local magnetic moment of a quantum dot coupled to a normal metallic lead and a topological superconducting wire hosting Majorana modes at the ends. By means of simple analytical tools and numerical renormalization group calculations we show that the proximity of Majorana mode reduces the magnetic moment from $1/4$, characteristic of a free spin $1/2$, to $1/16$. The coupling to the normal lead then causes the Kondo effect, such that the magnetic moment is fully screened below the Kondo temperature. The latter is vastly increased for strong coupling to Majorana mode.