Hirahara T, Otrokov M M, Sasaki T T, Sumida K, Tomohiro Y, Kusaka S, Okuyama Y, Ichinokura S, Kobayashi M, Takeda Y, Amemiya K, Shirasawa T, Ideta S, Miyamoto K, Tanaka K, Kuroda S, Okuda T, Hono K, Eremeev S V, Chulkov E V
Department of Physics, Tokyo Institute of Technology, Tokyo, 152-8551, Japan.
Centro de Física de Materiales, CFM-MPC, Centro Mixto CSIC-UPV/EHU, Apdo.1072, 20080, San Sebastián/Donostia, Basque Country, Spain.
Nat Commun. 2020 Sep 24;11(1):4821. doi: 10.1038/s41467-020-18645-9.
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 MnBiTe/BiTe where multiple magnetic layers are inserted into the topmost quintuple layer of the original topological insulator BiTe. 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 MnBiTe/BiTe. Magnetic measurements show that there are two distinct Mn components in the system that corresponds to the two heterostructures; MnBiTe/BiTe is paramagnetic at 6 K while MnBiTe/BiTe 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，如量子反常霍尔效应。在此，我们制备了一种新型磁性拓扑异质结构MnBiTe/BiTe，其中多个磁性层被插入到原始拓扑绝缘体BiTe的最顶层五元层中。在16K时观察到一个具有40 - 75meV能隙的大质量狄拉克锥（DC）。通过追踪温度演变，发现该能隙随温度升高逐渐减小，并且在200 - 250K左右发生从大质量到无质量DC的突变。结构分析表明样品中还含有MnBiTe/BiTe。磁性测量表明系统中有两种不同的Mn组分，分别对应两种异质结构；MnBiTe/BiTe在6K时是顺磁性的，而MnBiTe/BiTe是具有负磁滞（临界温度约20K）的铁磁性。这种新型异质结构对未来的器件应用可能具有重要意义。
