Magnetically-Confined Bound States in Rashba Systems

TL;DR

This paper demonstrates that magnetic domain walls in Rashba systems can host isolated bound states and quantum channels, which are robust and experimentally accessible, expanding potential applications in spintronics.

Contribution

It analytically and numerically proves the existence of magnetically-confined bound states in Rashba nanowires and extends the concept to two-dimensional systems with strong spin-orbit interaction.

Findings

Bound states exist below bulk energy levels in Rashba nanowires with magnetic domain walls.

Magnetic confinement induces a non-degenerate dispersive band in 2D systems.

The magnetic confinement is robust against disorder and parameter changes.

Abstract

A Rashba nanowire is subjected to a magnetic field that assumes opposite signs in two sections of the nanowire, and, thus, creates a magnetic domain wall. The direction of magnetic field is chosen to be perpendicular to the Rashba spin-orbit vector such that there is only a partial gap in the spectrum. Nevertheless, we prove analytically and numerically that such a domain wall hosts a bound state whose energy is at bottom of the spectrum below the energy of all bulk states. Thus, this magnetically-confined bound state is well-isolated and can be accessed experimentally. We further show that the same type of magnetic confinement can be implemented in two-dimensional systems with strong spin-orbit interaction. A quantum channel along the magnetic domain wall emerges with a non-degenerate dispersive band that lies energetically below the bulk states. We show that this magnetic confinement is robust against disorder and various parameter variations.