Gate-controlled spin-splitting in quantum dots with ferromagnetic leads in the Kondo regime

TL;DR

This paper investigates how gate voltage influences spin-splitting in quantum dots with ferromagnetic leads within the Kondo regime, revealing dependence on the density of states shape and introducing a new logarithmic divergence.

Contribution

It provides a detailed analysis of gate voltage effects on spin-splitting, highlighting the role of density of states shape and identifying a novel logarithmic divergence in the Kondo regime.

Findings

Spin-splitting depends on the DOS shape and gate voltage.

Gate voltage can control the magnitude and sign of spin-splitting.

A new logarithmic divergence in spin-splitting is identified.

Abstract

The effect of a gate voltage ($V_g$) on the spin-splitting of an electronic level in a quantum dot (QD) attached to ferromagnetic leads is studied in the Kondo regime using a generalized numerical renormalization group technique. We find that the $V_g$-dependence of the QD level spin-splitting strongly depends on the shape of the density of states (DOS). For one class of DOS shapes there is nearly no $V_g$-dependence, for another, $V_g$ can be used to control the magnitude and sign of the spin-splitting, which can be interpreted as a local exchange magnetic field. We find that the spin-splitting acquires a new type of logarithmic divergence. We give an analytical explanation for our numerical results and explain how they arise due to spin-dependent charge fluctuations.