Spin selective transport through Aharonov-Bohm and Aharonov-Casher triple quantum dot systems

TL;DR

This paper investigates spin filtering in triple quantum dot systems under magnetic fields, analyzing two configurations with localized spins and Rashba spin-orbit coupling, revealing tunable spin valve behavior with minor Kondo effects.

Contribution

It introduces an improved effective Hamiltonian approach for analyzing spin transport in quantum dots, enhancing the accuracy of previous models and exploring two distinct spin filtering mechanisms.

Findings

Both systems act as magnetic field tunable spin valves.

Correlation effects like Kondo physics are minor at high magnetic fields.

The study compares localized spin and Rashba coupling configurations.

Abstract

We calculate the conductance through a system of three quantum dots under two different sets of conditions that lead to spin filtering effects under an applied magnetic field. In one of them, a spin is localized in one quantum dot, as proposed by Delgado et al. [Phys. Rev. Lett. 101, 226810 (2008)]. In the other one, all dots are equivalent by symmetry and the system is subject to a Rashba spin-orbit coupling. We solve the problem using a simple effective Hamiltonian for the low-energy subspace, improving the accuracy of previous results. We obtain that correlation effects related to the Kondo physics play a minor role for parameters estimated previously and high enough magnetic field. Both systems lead to a magnetic field tunable "spin valve".