Domain wall of a ferromagnet on a three-dimensional topological insulator

TL;DR

This paper theoretically investigates the properties of domain walls in a ferromagnet on a three-dimensional topological insulator, revealing their charge, controllability by electric fields, and dependence on Fermi energy, with implications for spintronics.

Contribution

It introduces the concept that domain walls in such systems are charged and controllable, depending on Fermi energy and magnetic coupling, which is a novel insight.

Findings

Domain walls carry charge and can be controlled electrically.

Chirality and stability depend on Fermi energy and magnetic coupling.

Potential applications in spintronics are suggested.

Abstract

Topological insulators (TIs) show rich phenomena and functions which can never be realized in ordinary insulators. Most of them come from the peculiar surface or edge states. Especially, the quantized anomalous Hall effect (QAHE) without an external magnetic field is realized in the two-dimensional ferromagnet on a three-dimensional TI which supports the dissipationless edge current. Here we demonstrate theoretically that the domain wall of this ferromagnet, which carries edge current, is charged and can be controlled by the external electric field. The chirality and relative stability of the Neel wall and Bloch wall depend on the position of the Fermi energy as well as the form of the coupling between the magnetic moments and orbital of the host TI. These findings will pave a path to utilize the magnets on TI for the spintronics applications.