Antiferromagnetic order in MnBi2Te4 films grown on Si(111) by molecular beam epitaxy

TL;DR

This study demonstrates the successful growth of high-quality, stoichiometric MnBi2Te4 films on Si(111) using MBE, exhibiting intrinsic antiferromagnetic order with properties comparable to bulk crystals, advancing the development of magnetic topological insulators.

Contribution

It presents the first detailed characterization of stoichiometric MnBi2Te4 films grown by MBE with confirmed antiferromagnetic order and structural integrity.

Findings

Films show antiferromagnetic order with Neel temperature of 19 K

Structural defects typical for epitaxial van-der-Waals layers are analyzed

Resistivity of 1.6 mOhm cm comparable to bulk crystals

Abstract

MnBi2Te4 has recently been predicted and shown to be a magnetic topological insulator with intrinsic antiferromagnetic order. However, it remains a challenge to grow stoichiometric MnBi2Te4 films by molecular beam epitaxy (MBE) and to observe pure antiferromagnetic order by magnetometry. We report on a detailed study of MnBi2Te4 films grown on Si(111) by MBE with elemental sources. Films of about 100 nm thickness are analyzed in stoichiometric, structural, magnetic and magnetotransport properties with high accuracy. High-quality MnBi2Te4 films with nearly perfect septuple-layer structure are realized and structural defects typical for epitaxial van-der-Waals layers are analyzed. The films reveal antiferromagnetic order with a Neel temperature of 19 K, a spin-flop transition at a magnetic field of 2.5 T and a resistivity of 1.6 mOhm cm. These values are comparable to that of bulk MnBi2Te4 crystals. Our results provide an important basis for realizing and identifying single-phase MnBi2Te4 films with antiferromagnetic order grown by MBE.