Confinement of spin-orbit induced Dirac states in quantum point contacts

TL;DR

This paper demonstrates how strong Rashba spin-orbit interaction and magnetic fields create controllable Dirac states in quantum point contacts, enabling spin current and spin pumping at zero bias, with experimental feasibility in p-type systems.

Contribution

It introduces a semiclassical solution to the quantum transmission problem revealing emergent Dirac states induced by spin-orbit and magnetic fields in quantum point contacts.

Findings

Dirac states form at the center of the constriction under strong Rashba and magnetic field.

Resonances carry spin current and become bound at high magnetic fields.

The effect can be controlled via external electric and magnetic fields, enabling spin pumping.

Abstract

The quantum transmission problem for a particle moving in a quantum point contact in the presence of a Rashba spin-orbit interaction and applied magnetic field is solved semiclassically. A strong Rashba interaction and parallel magnetic field form emergent Dirac states at the center of the constriction, leading to the appearance of resonances which carry spin current and become bound at high magnetic fields. These states can be controlled in situ by modulation of external electric and magnetic fields, and can be used to turn the channel into a spin pump which operates at zero bias. It is shown that this effect is currently experimentally accessible in $p$-type quantum point contacts.