Modulation of Dirac electrons in epitaxial Bi2Se3 ultrathin films on van der Waals ferromagnet Cr2Si2Te6
Modulation of Dirac electrons in epitaxial Bi2Se3 ultrathin films on van der Waals ferromagnet Cr2Si2Te6
复制标题
DOI：
10.1103/physrevmaterials.4.084202
复制
发表时间：
2020-08
期刊：
影响因子：
--
通讯作者：
Takemi Kato;K. Sugawara;Naohiro Ito;K. Yamauchi;Takumi Sato;T. Oguchi;Takashi Takahashi;Y. Shiomi
中科院分区：
文献类型：
--
作者：
Takemi Kato;K. Sugawara;Naohiro Ito;K. Yamauchi;Takumi Sato;T. Oguchi;Takashi Takahashi;Y. Shiomi
我们通过角分辨光电子能谱研究了拓扑绝缘体Bi₂Se₃ 超薄薄膜在范德华铁磁体Cr₂Si₂Te₆（CST）上外延生长时的狄拉克锥态及其调制情况。我们观察到，在CST上的6个五原子层（QL）Bi₂Se₃ 中存在无带隙的狄拉克锥表面态，而在2个五原子层的Bi₂Se₃ 中，狄拉克锥呈现出0.37电子伏特的带隙。有趣的是，该带隙比Bi₂Se₃ 薄膜在Si(111)上的带隙大得多。我们还发现，在CST的铁磁转变过程中，带隙大小没有明显变化，这表明磁近邻效应的特征长度和能量尺度非常小。目前的研究结果表明，界面耦合在调控拓扑绝缘体杂化材料中的狄拉克电子方面起着关键作用。
We investigated the Dirac-cone state and its modulation when an ultrathin film of topological insulator Bi2Se3 was epitaxially grown on a van-der-Waals ferromagnet Cr2Si2Te6 (CST) by angle-resolved photoemission spectroscopy. We observed a gapless Dirac-cone surface state in 6 quintuple-layer (QL) Bi2Se3 on CST, whereas the Dirac cone exhibits a gap of 0.37 eV in 2QL counterpart. Intriguingly, this gap is much larger than those for Bi2Se3 films on Si(111). We also revealed no discernible change in the gap magnitude across the ferromagnetic transition of CST, suggesting the very small characteristic length and energy scale of the magnetic proximity effect. The present results suggest a crucial role of interfacial coupling for modulating Dirac electrons in topological-insulator hybrids.