Flat Chern Band from Twisted Bilayer ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$

Flat Chern Band from Twisted Bilayer ${MnBi}_{2} {Te}_{4}$

Biao Lian, Zhaochen Liu, Yuanbo Zhang, and Jing Wang

Phys. Rev. Lett. 124, 126402 – Published 26 March 2020

Abstract

We construct a continuum model for the moiré superlattice of twisted bilayer ${MnBi}_{2} {Te}_{4}$ , and study the band structure of the bilayer in both ferromagnetic (FM) and antiferromagnetic (AFM) phases. We find the system exhibits highly tunable Chern bands with Chern number up to 3. We show that a twist angle of 1° turns the highest valence band into a flat band with Chern number $\pm 1$ that is isolated from all other bands in both FM and AFM phases. This result provides a promising platform for realizing time-reversal breaking correlated topological phases, such as fractional Chern insulator and $p + i p$ topological superconductor. In addition, our calculation indicates that the twisted stacking facilitates the emergence of quantum anomalous Hall effect in ${MnBi}_{2} {Te}_{4}$ .

Received 19 August 2019
Accepted 5 March 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.126402

Physics Subject Headings (PhySH)

Topological materials

Chern insulators Strongly correlated systems Two-dimensional electron system

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Biao Lian^1,*, Zhaochen Liu², Yuanbo Zhang^2,3, and Jing Wang^2,3,†

¹Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544, USA
²State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China
³Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China