Metal-insulator transition in a quantum wire driven by a modulated Rashba spin-orbit coupling

TL;DR

This paper investigates how a modulated Rashba spin-orbit coupling in a quantum wire induces a quantum phase transition to an insulating state, with potential applications in spin transistor technology.

Contribution

It demonstrates that a smoothly modulated Rashba coupling can drive a quantum phase transition in a quantum wire, robust against electron-electron interactions, with practical implications for spintronics.

Findings

Rashba modulation induces a nonmagnetic insulating state at commensurate band filling.

Charge and spin gaps scale with the modulation amplitude and interaction strength.

Estimated charge gap size suggests feasibility for spin transistor applications.

Abstract

We study the ground-state properties of electrons confined to a quantum wire and subject to a smoothly modulated Rashba spin-orbit coupling. When the period of the modulation becomes commensurate with the band filling, the Rashba coupling drives a quantum phase transition to a nonmagnetic insulating state. Using bosonization and a perturbative renormalization group approach, we find that this state is robust against electron-electron interactions. The gaps to charge- and spin excitations scale with the amplitude of the Rashba modulation with a common interaction-dependent exponent. An estimate of the expected size of the charge gap, using data for a gated InAs heterostructure, suggests that the effect can be put to practical use in a future spin transistor design.