论文标题
磁性拓扑绝缘子MNBI的磁性和电子结构$ _2 $ SE $ _4 $
Magnetic Properties and Electronic Structure of Magnetic Topological Insulator MnBi$_2$Se$_4$
论文作者
论文摘要
固有的磁性拓扑绝缘子MNBI $ _2 $ x $ _4 $（x = SE，TE）是有望在实现与磁性秩序上与对称性破坏有关的各种新型拓扑状态方面有希望的候选人。尽管MNBI $ _2 $ TE $ _4 $取得了很大的进展，但由于材料综合所需的三角阶段的材料的难度，对MNBI $ _2 $ SE $ _4 $的研究一直缺乏。在这里，我们报告了多层trigonal mnbi $ _2 $ se $ _4 $与交替层分子梁外观的合成。原子分辨率扫描透射电子显微镜（STEM）和扫描隧道显微镜（STM）确定了有序的多层范德华（VDW）晶体，具有与三角形结构一致。系统的厚度依赖性磁力测定学研究说明了理论预测的分层抗磁磁有序。角度分辨光发射光谱（ARPES）揭示了MNBI $ _2 $ SE $ _4 $的无间隙狄拉克状表面状态，这表明MNBI $ _2 $ SE $ _4 $是磁性订购温度上方的拓扑绝缘子。这些系统的研究表明，MNBI $ _2 $ SE $ _4 $是探索分层抗磁性拓扑绝缘子的丰富拓扑阶段的有前途的候选人。
The intrinsic magnetic topological insulators MnBi$_2$X$_4$ (X = Se, Te) are promising candidates in realizing various novel topological states related to symmetry breaking by magnetic order. Although much progress had been made in MnBi$_2$Te$_4$, the study of MnBi$_2$Se$_4$ has been lacking due to the difficulty of material synthesis of the desired trigonal phase. Here, we report the synthesis of multilayer trigonal MnBi$_2$Se$_4$ with alternating-layer molecular beam epitaxy. Atomic-resolution scanning transmission electron microscopy (STEM) and scanning tunneling microscopy (STM) identify a well-ordered multilayer van der Waals (vdW) crystal with septuple-layer base units in agreement with the trigonal structure. Systematic thickness-dependent magnetometry studies illustrate the layered antiferromagnetic ordering as predicted by theory. Angle-resolved photoemission spectroscopy (ARPES) reveals the gapless Dirac-like surface state of MnBi$_2$Se$_4$, which demonstrates that MnBi$_2$Se$_4$ is a topological insulator above the magnetic ordering temperature. These systematic studies show that MnBi$_2$Se$_4$ is a promising candidate for exploring the rich topological phases of layered antiferromagnetic topological insulators.
