Modulation of Dirac electrons in epitaxial Bi2Se3 ultrathin films on van-der-Waals ferromagnet Cr2Si2Te6

Abstract

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.

References in corpus (9)

• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Topological Field Theory of Time-Reversal Invariant Insulators
• High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator
• Trajectory of Anomalous Hall Effect toward the Quantized State in a Ferromagnetic Topological Insulator
• Direct Evidence for the Dirac-Cone Topological Surface States in Ternary Chalcogenide TlBiSe2
• Epitaxial growth of topological insulator Bi2Se3 film on Si(111) with atomically sharp interface
• Large Anomalous Hall Effect in Topological Insulators with Proximitized Ferromagnetic Insulators
• Record-High Proximity-Induced Anomalous Hall Effect in (Bi${}_x$Sb${}_{1-x}$)2Te${}_3$ Thin Film Grown on CrGeTe${}_3$ Substrate
• Work function of bulk-insulating topological insulator Bi2-xSbxTe3-ySey