Fluctuations of spin transport through chaotic quantum dots with spin-orbit coupling

TL;DR

This paper analyzes how spin-orbit coupling causes fluctuations in spin and charge transport through chaotic quantum dots, using random matrix theory to estimate typical current scales and their implications for spintronic devices.

Contribution

It introduces a random matrix theory approach to quantify fluctuations in spin and charge currents in chaotic quantum dots with strong spin-orbit coupling, including entangled currents.

Findings

Quantifies typical charge and spin current fluctuations due to spin-orbit coupling.

Shows larger fluctuations when currents are entangled between leads.

Connects density matrix formalism to spin-conductance models.

Abstract

As devices to control spin currents using the spin-orbit interaction are proposed and implemented, it is important to understand the fluctuations that spin-orbit coupling can impose on transmission through a quantum dot. Using random matrix theory, we estimate the typical scale of transmitted charge and spin currents when a spin current is injected into a chaotic quantum dot with strong spin-orbit coupling. These results have implications for the functioning of the spin transistor proposed by Schliemann, Egues, and Loss. We use a density matrix formalism appropriate for treating arbitrary input currents and indicate its connections to the widely used spin-conductance picture. We further consider the case of currents entangled between two leads, finding larger fluctuations.