Spin and Polarized Current from Coulomb Blockaded Quantum Dots

TL;DR

This paper investigates spin transitions and polarization in Coulomb blockaded GaAs quantum dots, revealing spin-dependent transport phenomena and demonstrating that emitted current is polarized along the magnetic field direction.

Contribution

It provides direct measurements of spin states and polarization in quantum dots, combining transport spectroscopy with spin-sensitive electron focusing techniques.

Findings

Observation of both spin-increasing and spin-decreasing transitions

Measurement of g-factors down to a single electron

Emitted current polarization aligns with magnetic field direction

Abstract

We report measurements of spin transitions for GaAs quantum dots in the Coulomb blockade regime, and compare ground and excited state transport spectroscopy to direct measurements of the spin polarization of emitted current. Transport spectroscopy reveals both spin-increasing and spin-decreasing transitions as well as higher-spin ground states, and allows g-factors to be measured down to a single electron. The spin of emitted current in the Coulomb blockade regime, measured using spin-sensitive electron focusing, is found to be polarized along the direction of the applied magnetic field regardless of the ground state spin transition.