Realization of an intrinsic, ferromagnetic topological state in MnBi8Te13

TL;DR

This paper reports the discovery of MnBi8Te13 as the first intrinsic ferromagnetic topological insulator with a clean band structure, enabling exploration of novel topological phenomena like the quantum anomalous Hall effect.

Contribution

The study demonstrates the design, synthesis, and characterization of MnBi8Te13 as an intrinsic ferromagnetic topological material with a well-defined low-energy band structure.

Findings

MnBi8Te13 exhibits long-range ferromagnetism below 10.5 K.

It is an intrinsic ferromagnetic axion insulator.

The material shows potential for observing quantized topological effects.

Abstract

The interplay between topology and magnetism is essential for realizing novel topological states including the axion insulator, the magnetic Weyl semimetal, etc. An intrinsically ferromagnetic topological material with only the topological bands at the charge neutrality energy has so far remained elusive. By rationally designing the natural heterostructure consisting of [MnBi2Te4] septuple layers and [Bi2Te3] quintuple layers, we report MnBi8Te13 as the first intrinsic ferromagnetic topological material with clean low-energy band structure. Based on the thermodynamic, transport and neutron diffraction measurements, our data show that despite the adjacent [MnBi2Te4] being 44.1 {\AA} apart, MnBi8Te13 manifests long-range ferromagnetism below 10.5 K with strong coupling between magnetism and charge carriers. Our first-principles calculations and angle-resolved photoemission spectroscopy measurements further demonstrate that MnBi8Te13 is an intrinsic ferromagnetic axion state. Therefore, MnBi8Te13 serves as an ideal system to investigate rich emergent phenomena, including the quantized anomalous Hall effect and quantized topological magnetoelectric effect.