van der Waals Epitaxy of Bi Nanowires and Bi₂Se₃ Thin Films on an Antiferromagnetic Substrate of CoNb₃S₆

Abstract

The combination of a topological insulator and an antiferromagnet is expected to exhibit the quantum anomalous Hall effect due to the breaking of the time-reversal symmetry. As a layered antiferromagnet, CoNb 3 S 6 was recently found to exhibit an anomalous Hall effect below the Neél temperature (T N = 29 K). Here, we report the controllable growth of Bi nanowires and Bi 2 Se 3 thin films on CoNb 3 S 6 substrates using molecular beam epitaxy. The composition and morphology of the as-prepared Bi nanowires and Bi 2 Se 3 thin films were studied by atomic force microscopy, X-ray photoelectron spectroscopy, and scanning tunneling microscopy. We found that the as-grown Bi nanowires with abundant sizes are oriented along high-symmetry directions of the substrate, forming firework-like structures. Such firework-like structures of Bi nanowires exhibit a high edge-to-surface ratio as well as a strong anisotropy, highly desirable for photoelectric devices and industrial catalysts. The absence of oxidation peaks verifies that the asprepared samples are of high quality and air stability, very promising for applications.

Structures of α-BixSb1–x Alloys Formed on the TiSe2 Substrates

“…TiSe 2 crystallizes in the hexagonal Bravais lattice with the space group D 3 d 3 ( P 3̅ m 1, 164), which mismatches with the orthorhombic lattice of α-Bi and α-Sb (Figure a). As the TiSe 2 surface is terminated with Se atoms that are chemically saturated, the coupling between the epilayers and the TiSe 2 substrates is of van der Waals (vdW) type Figure b shows a large-scale STM image of the α-Bi prepared on the TiSe 2 substrate at RT.…”

“…As the TiSe 2 surface is terminated with Se atoms that are chemically saturated, the coupling between the epilayers and the TiSe 2 substrates is of van der Waals (vdW) type. 21 Figure 1b shows a large-scale STM image of the α-Bi prepared on the TiSe 2 substrate at RT. Line profile analysis (Figure 1d) along the red line marked in Figure 1b reveals a step height of 0.69 ± 0.01 nm, similar to bilayer Bi(110) grow on Fe 3 GeTe 2 .…”

Epitaxy of Antimonene Thin Films with Screw Dislocations for the Application of Saturable Absorbers

“…Deposition of ∼3 ML of Sb at a growth temperature of 490 K leads to the formation of multilayer β-Sb islands on FGT substrates, as depicted in Figure e. It is evident that the successive epilayers have already formed prior to the completion of the initial layers, suggesting a Volmer–Weber growth mode. , The zoomed-in STM image (Figure f) displays the existence of hexagonal moiré patterns superposed on the periodic atomic structure of β-Sb. Such a moiré pattern has a height oscillation of ∼34 pm and a periodicity of ∼10.4 nm, 26 times the period of the FGT lattice.…”