Controllable Synthesis of High-Quality Magnetic Topological Insulator MnBi₂Te₄ and MnBi₄Te₇ Multilayers by Chemical Vapor Deposition.

Abstract

With a nontrivial topological band and intrinsic magnetic order, two-dimensional (2D) MnBi₂Te₄-family materials exhibit great promise for exploring exotic quantum phenomena and potential applications. However, the synthesis of 2D MnBi₂Te₄-family materials via chemical vapor deposition (CVD), which is essential for advancing device applications, still remains a significant challenge since it is difficult to control the reactions among multi-precursors and form pure phases. Here, we report a controllable synthesis of high-quality magnetic topological insulator MnBi₂Te₄ and MnBi₄Te₇ multilayers via an evaporation-rate-controlled CVD approach. The multilayers are grown on a mica substrate epitaxially, exhibiting a regular triangle shape. By controlling growth temperatures, the thickness and lateral size of the 2D MnBi₂Te₄ are well regulated. Furthermore, the magneto-transport measurements clearly reveal multistep spin-flop transitions for both odd- and even-number-layered MnBi₂Te₄ multilayers. Our study marks a significant stride toward future transformative applications in devices based on high-quality, edge- and thickness-controlled 2D magnetic topological quantum materials.