Current Induced Hole Spin Polarization in Quantum Dot via Chiral Quasi Bound State

TL;DR

This paper proposes a novel mechanism for inducing complete spin polarization of holes in quantum dots via current, leveraging spin-orbit effects and chiral quasi-bound states, applicable across various semiconductor materials.

Contribution

It introduces a new spin polarization mechanism based on spin-orbit splitting and chiral states, differing from traditional linear coupling methods.

Findings

Exponential bias induces 100% hole spin polarization.

Chiral quasi-bound states facilitate spin-dependent tunneling.

Applicable to GaAs, Si, and Ge nanostructures.

Abstract

We put forward a mechanism for current induced spin polarization for a hole in a quantum dot side-coupled to a quantum wire, that is based on the spin-orbit splitting of the valence band. We predict that in a stark contrast with the traditional mechanisms based on the linear in momentum spin-orbit coupling, an exponentially small bias applied to the quantum wire with heavy holes is enough to create the 100% spin polarization of a localized light hole. Microscopically, the effect is related with the formation of chiral quasi bound states and the spin dependent tunneling of holes from the quantum wire to the quantum dot. This novel current induced spin polarization mechanism is equally relevant for the GaAs, Si and Ge based semiconductor nanostructures.