Current and Shot Noise in a Quantum Dot Coupled to Ferromagnetic Leads in the Large U Limit

TL;DR

This paper investigates how ferromagnetic lead polarization affects current and shot noise in a quantum dot using nonequilibrium Green function techniques, revealing polarization-dependent differences in conductance and noise.

Contribution

It provides general formulas for current and shot noise in a quantum dot with ferromagnetic leads, covering both parallel and antiparallel alignments, especially in the large U limit.

Findings

Differential conductance and shot noise differ significantly for spin configurations at high polarization in parallel alignment.

Similar conductance and noise properties are observed at low polarization in parallel and in all polarizations for antiparallel alignment.

The study highlights the impact of lead polarization on transport properties in quantum dots.

Abstract

Using the Keldysh nonequilibrium Green function technique, we study the current and shot noise spectroscopy of a single interacting quantum dot coupled to two ferromagnetic leads with different polarizations. The polarizations of leads can be both parallel and antiparallel alignments. General formulas of current and shot noise are obtained, which can be applied in both the parallel and antiparallel alignment cases. We show that for large polarization value, the differential conductance and shot noise are completely diferent for spin up and spin down configurations in the parallel alignment case. However, the differential conductance and shot noise have the similar properties for parallel alignment case in the small polarization value and for antiparallel alignment case in any polarization value.