Yitao Chen received his bachelor's degree in Polymer Materials from Southwest Jiaotong University and his master's degree in Condensed Matter Physics from Hokkaido University. He is currently a second-year Ph.D. student in the NIMS Joint Graduate School Program and a NIMS Junior Researcher.

Moiré superlattices formed by crystallographic misorientation or lattice mismatch generate long-wavelength periodic potentials and reconstruct electronic states into moiré minibands, which may promote flat-band formation [1].

In our previous work, one- and two-bilayer (BL) Sb honeycomb layers deposited on Bi(111)/Si(111) formed clear moiré patterns because of the lattice mismatch between antimonene and Bi(111). Scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) revealed a pronounced feature near the Fermi level associated with a saddle point in the band structure [2]. To improve the crystallinity of the moiré superlattice, Sb was grown on the Bi substrate at approximately 100 K.

Compared with room-temperature growth, the low-temperature-grown 1BL samples exhibit a higher degree of atomic-scale order and a more ordered moiré superstructure. Statistical analysis reveals a narrower distribution of the moiré lattice constant, defined as the distance between neighboring equivalent stacking sites. We also found that the moiré lattice constant is approximately 10% smaller than that of the room-temperature-grown samples, suggesting that the growth conditions affect the moiré structure and may consequently modify the electronic states.

Scanning tunneling spectroscopy (STS) of the low-temperature-grown 1BL moiré further reveals a clear pair of peaks at approximately ±50 mV, which was not resolved in our previous measurements. Although the spectral line shape resembles the calculated density of states for AB stacking [2], similar double-peak features are observed at AA, AC, and some AB regions in the present samples. This observation suggests that the modified moiré potential may influence the electronic structure associated with the van Hove singularity (VHS), rather than the spectral features being determined solely by the local stacking configuration. Further theoretical calculations are required to clarify the microscopic origin of this behavior.

1. Y. Cao et al., Nature 556, 43–50 (2018), DOI: 10.1038/nature26160
2. T. Nakamura et al., Communications Materials 5, 167 (2024), DOI: 10.1038/s43246-024-00615-z