Electrically tunable spin polarization of chiral edge modes in a quantum anomalous Hall insulator

TL;DR

This paper theoretically demonstrates that spin polarization of chiral edge modes in a quantum anomalous Hall insulator can be electrically controlled and detected, advancing potential spintronics applications.

Contribution

It introduces a method to manipulate and measure spin polarization of chiral edge modes using gate voltages and ferromagnetic contacts, which was not previously established experimentally.

Findings

Spin polarization can be tuned by gate voltage or Fermi energy.

Spin information can be extracted via ferromagnetic leads.

Electrical control and detection of spin polarization are feasible.

Abstract

In the quantum anomalous Hall effect, chiral edge modes are expected to conduct spin polarized current without dissipation and thus hold great promise for future electronics and spintronics with low energy consumption. However, spin polarization of chiral edge modes has never been established in experiments. In this work, we theoretically study spin polarization of chiral edge modes in the quantum anomalous Hall effect, based on both the effective model and more realistic tight-binding model constructed from the first principles calculations. We find that spin polarization can be manipulated by tuning either a local gate voltage or the Fermi energy. We also propose to extract spin information of chiral edge modes by contacting the quantum anomalous Hall insulator to a ferromagnetic (FM) lead. The establishment of spin polarization of chiral edge modes, as well as the manipulation and detection in a fully electrical manner, will pave the way to the applications of the quantum anomalous Hall effect in spintronics.