Materials that possess nontrivial topology and magnetism is known to exhibit exotic quantum phenomena such as the quantum anomalous Hall effect. Here, we fabricate a novel magnetic topological heterostructure Mn₄Bi₂Te₇/Bi₂Te₃ where multiple magnetic layers are inserted into the topmost quintuple layer of the original topological insulator Bi₂Te₃. A massive Dirac cone (DC) with a gap of 40–75 meV at 16 K is observed. By tracing the temperature evolution, this gap is shown to gradually decrease with increasing temperature and a blunt transition from a massive to a massless DC occurs around 200–250 K. Structural analysis shows that the samples also contain MnBi₂Te₄/Bi₂Te₃. Magnetic measurements show that there are two distinct Mn components in the system that corresponds to the two heterostructures; MnBi₂Te₄/Bi₂Te₃ is paramagnetic at 6 K while Mn₄Bi₂Te₇/Bi₂Te₃ is ferromagnetic with a negative hysteresis (critical temperature ~20 K). This novel heterostructure is potentially important for future device applications.

已知具有非平凡拓扑结构和磁性的材料会表现出奇异的量子现象，例如量子反常霍尔效应。在这里，我们制造了一种新的磁性拓扑异质结构 Mn ₄ Bi ₂ Te ₇ /Bi ₂ Te ₃，其中将多个磁性层插入到原始拓扑绝缘体 Bi ₂ Te ₃的最顶层五元层中. 观察到一个巨大的狄拉克锥 (DC)，在 16 K 下具有 40-75 meV 的间隙。通过追踪温度演变，显示该间隙随着温度升高而逐渐减小，并且在 200–250 K 附近发生从有质量 DC 到无质量 DC 的钝转变。结构分析表明，样品还包含 MnBi ₂ Te ₄ /Bi ₂ Te ₃ . 磁性测量表明，系统中有两种不同的 Mn 成分对应于两种异质结构；MnBi ₂ Te ₄ /Bi ₂ Te ₃在 6 K 是顺磁性的，而 Mn ₄ Bi ₂ Te ₇ /Bi ₂ Te ₃是铁磁性的，具有负磁滞（临界温度 ~20 K）。这种新颖的异质结构对于未来的设备应用可能很重要。