Spin-polarized transport in quadruple quantum dots attached to ferromagnetic leads

Abstract

Motivated by the experimental evidence of the Nagaoka ferromagnetism in quantum dot systems by Dehollain et al [1], we search for possible confirmation of such kind of ferromagnetism by analyzing the spin-resolved transport properties of a quadruple quantum dot system focusing on the linear response regime. In particular, we consider four quantum dots arranged in a two-by-two square lattice, coupled to external ferromagnetic source and drain electrodes. Turning on and off the specific conditions for the Nagaoka ferromagnetism to occur by changing the value of the intra-dot Coulomb interactions, we determine the transport coefficients, including the linear conductance, tunnel magnetoresistance and current spin polarization. We show that a sign change of the current spin polarization may be an indication of a ferromagnetic order of Nagaoka type which develops in the system.

arXiv comment5 pages, 4 figures, open access

References in corpus (11)

• Tunnel magnetoresistance of quantum dots coupled to ferromagnetic leads in the sequential and cotunneling regimes
• Minimal Self-Contained Quantum Refrigeration Machine Based on Four Quantum Dots
• Nagaoka ferromagnetism observed in a quantum dot plaquette
• A few-electron quadruple quantum dot in a closed loop
• Effects of anisotropy and Coulomb interactions on quantum transport in a quadruple quantum-dot structure
• Kondo screening of a high-spin Nagaoka state in a triangular quantum dot
• Ferromagnetism in Quantum Dot Plaquettes
• Quantum Phase Transition and Dynamically Enhanced Symmetry in Quadruple Quantum Dot System
• Coulomb interactions induced perfect spin filtering effect in a quadruple quantum-dot cell
• The influence of Coulomb correlations on nonequilibrium quantum transport in quadruple quantum-dot structure
• Observation of Kondo Effect in a Quadruple Quantum Dots