Many-Body Approch to Spin-Dependent Transport in Quantum Dot Systems

TL;DR

This paper introduces a diagram technique for Hubbard operators to analyze spin-dependent level renormalization in quantum dots, revealing significant effects on tunneling currents and resonant behavior influenced by lead magnetic order.

Contribution

It presents a novel diagrammatic approach to study spin-dependent interactions in quantum dots modeled by the Anderson Hamiltonian with two conduction bands.

Findings

Spin-dependent renormalization of localized levels due to kinematic interactions.

Decreased tunneling current in ferromagnetic leads compared to paramagnetic.

Spin-dependent resonant tunneling behavior observed with ferromagnetic leads.

Abstract

By means of a diagram technique for Hubbard operators we show the existence of a spin-dependent renormalization of the localized levels in an interacting region, e.g. quantum dot, modeled by the Anderson Hamiltonian with two conduction bands. It is shown that the renormalization of the levels with a given spin direction is due to kinematic interactions with the conduction sub-bands of the opposite spin. The consequence of this dressing of the localized levels is a drastically decreased tunneling current for ferromagnetically ordered leads compared to that of paramagnetically ordered leads. Furthermore, the studied system shows a spin-dependent resonant tunneling behaviour for ferromagnetically ordered leads.