Tunable 3D/2D magnetism in the (MnBi2Te4)(Bi2Te3)m topological insulators family

И И Климовских ,Vladimir Voroshnin,Giovanni Di Santo,И Р Амирасланов ,M M Otrokov ,N A Abdullayev ,Pedro M Echenique,D A Estyunin ,А В Королева ,S O Filnov ,A Ernst ,O E Tereshchenko ,Ziya S Aliev,А Г Рыбкин ,К А Кох ,Akio Kimura,L Petaccia ,Nazim Mamedov ,A M Shikin ,V N Zverev ,E V Shevchenko ,М Б Бабанлы ,Martin Hoffmann,Igor P Rusinov,С В Еремеев ,M Blanco-Rey ,Eugene V Chulkov

doi:10.1038/s41535-020-00255-9

Abstract

Feasibility of many emergent phenomena that intrinsic magnetic topological insulators (TIs) may host depends crucially on our ability to engineer and efficiently tune their electronic and magnetic structures. Here we report on a large family of intrinsic magnetic TIs in the homologous series of the van der Waals compounds (MnBi2Te4)(Bi2Te3)m with m = 0, ⋯, 6. Magnetic, electronic and, consequently, topological properties of these materials depend strongly on the m value and are thus highly tunable. The antiferromagnetic (AFM) coupling between the neighboring Mn layers strongly weakens on moving from MnBi2Te4 (m = 0) to MnBi4Te7 (m = 1) and MnBi6Te10 (m = 2). Further increase in m leads to change of the overall magnetic behavior to ferromagnetic (FM) one for (m = 3), while the interlayer coupling almost disappears. In this way, the AFM and FM TI states are, respectively, realized in the m = 0, 1, 2 and m = 3 cases. For large m numbers a hitherto-unknown topologically nontrivial phase can be created, in which below the corresponding critical temperature the magnetizations of the non-interacting 2D ferromagnets, formed by the MnBi2Te4 building blocks, are disordered along the third direction. The variety of intrinsic magnetic TI phases in (MnBi2Te4)(Bi2Te3)m allows efficient engineering of functional van der Waals heterostructures for topological quantum computation, as well as antiferromagnetic and 2D spintronics.

Highlights

Magnetism and topology can meet each other both in real space, giving rise to complex magnetic structures such as vortices or skyrmions, and in reciprocal momentum space, resulting in Weyl semimetal or magnetic topological insulator (MTI) phases
The first compound in the (MnBi2Te4)(Bi2Te3)m series is MnBi2Te4 (m = 0), which had been investigated previously and discovered to be the first AFM TI25,36. This system consists of septuple layer (SL) blocks stacked one on top of another
For m ≥ 1, the members of the (MnBi2Te4)(Bi2Te3)m family are comprised of alternating septuple (MnBi2Te4) and quintuple (Bi2Te3) layer blocks

Summary

Introduction

Magnetism and topology can meet each other both in real space, giving rise to complex magnetic structures such as vortices or skyrmions, and in reciprocal momentum space, resulting in Weyl semimetal or magnetic topological insulator (MTI) phases. Combined with the non-trivial topology of the (MnBi2Te4)(Bi2Te3)m compounds, these magnetic states give rise to the AFM and FM TI phases for m = 0, 1, 2 and m = 3, respectively.

Results

Conclusion