Hidden Patterns in a Weyl Kagome Semimetal

The study centres on Co3Sn2S2, a magnetic Weyl kagome system. The kagome lattice, a hexagonal network of interconnected triangles, has been a subject of intense scientific interest due to its distinctive geometry and potential for hosting topological phases. Co3Sn2S2, in particular, exhibits intriguing properties such as high-electron density flat bands, Dirac states, and the presence of Fermi arcs. These are unique properties of the electronic band structure that offer exciting possibilities for novel electronic and quantum devices.

The researchers investigated, led by Federico Mazzola, the surface terminations of Co3Sn2S2, focusing on how different terminations affect the connectivity of Weyl points, which are monopoles of Berry curvature responsible for anomalous Hall effects and topological surface states. Scanning tunnelling microscopy (STM) studies had suggested the presence of multiple surface terminations in Co3Sn2S2, and this research aimed to clarify their impact on electronic properties.

By utilizing micro-angle-resolved photoelectron spectroscopy (micro-ARPES) and first-principles calculations, the team measured the energy-momentum spectra and Fermi surfaces for different surface terminations of Co3Sn2S2. The results revealed that the type of termination significantly influenced the electronic properties and topological features of the material. Notably, the researchers observed termination-dependent Fermi arcs that connect Weyl points in distinct ways, suggesting that the surface environment plays a crucial role in shaping the material’s topological connectivity.

The study’s findings have broad implications for the field of materials science and quantum electronics. The ability to control topological properties by manipulating surface electrostatic potentials opens up new avenues for designing responsive magnetic spintronics devices and harnessing the unique electronic characteristics of materials like Co3Sn2S2.

This research represents a significant step toward understanding and harnessing topological phases in materials, paving the way for innovative applications in fields such as spintronics, superconductors, and low-voltage electronics. The study’s combination of experimental and theoretical approaches provides a comprehensive view of the interplay between surface terminations and topological properties, offering valuable insights for future material design and engineering.

The full article is available at the following link: https://doi.org/10.1021/acs.nanolett.3c02022