Using a molecular beam epitaxy system, we grew high-quality monolayer Mn islands in an ultrahigh vacuum environment. The island sizes ranged from 100 to 3000 atoms. STS measurements revealed that the two surface states of Mn shift with island size. In collaboration with theoretical calculations, we found that these surface states originate from the Mn atomic d-orbitals. The five different d-orbitals undergo crystal field splitting into different energy levels, and strain in small islands further affects the geometric structure, leading to energy shifts in specific symmetry-related d-orbitals. Additionally, small Mn islands on Ag(111) exhibit an unconventional 120° antiferromagnetic Néel structure, where the spin has an out-of-plane component that can be flipped by an external magnetic field. Our simulations indicate that within a ±0.5 T range, both the spin structure and the tip polarization direction undergo flipping. More precise continuous variable magnetic field experiments could verify the independent flipping of these two factors, further confirming our hypothesis. These findings provide deeper insights into the development of nanoscale electronic and magnetic devices.

In the Bi/Al(111) system, we identified four distinct structures. Using STM measurements, we obtained atomic-resolution images and resolved the top-layer atomic arrangement. While a complete structural determination requires further collaboration with theoretical experts, our study lays the foundation for exploring this system. Among these phases, the Kagome structure exhibits a flat and defect-free nature, making it a promising platform for future studies. By utilizing ARPES, we can further probe its electronic band structure. Moreover, the well-ordered and smooth nature of these structures allows for the potential growth of other elements on top, offering opportunities to investigate novel physical phenomena.