Zener quantum dot spin filter in a carbon nanotube

TL;DR

This paper predicts a new spin filter device in semiconducting carbon nanotubes that uses a Zener quantum dot and magnetic field to achieve bipolar spin filtering, with theoretical validation.

Contribution

It introduces a novel spin filter design based on Zener quantum dots in carbon nanotubes, combining electrostatic gating and magnetic field effects, supported by theoretical modeling.

Findings

Resonant tunneling in Zener quantum dots enables spin filtering.

Magnetic field causes resonance splitting, producing bipolar spin filtering.

Theoretical models agree well with tight-binding calculations.

Abstract

We predict and analyze a novel spin filter in semiconducting carbon nanotubes. By using local electrostatic gates, the conduction and valence bands can be modulated to form a double-barrier structure. The confined region below the valence band defines a Zener quantum dot, which exhibits resonant tunneling. The resonances split in a magnetic field to make a bipolar spin filter for applications in spintronics and quantum information processing. We model this using k*p envelope function theory and show that this is in excellent agreement with a corresponding tight-binding calculation.