Tantalum disulfide is a mysterious material. According to textbook theory, it should be a conducting metal, but in the real world, it acts like an insulator. Using a scanning tunneling microscope, researchers from the RIKEN Center for Emergent Matter Science have taken a high-resolution look at the structure of the material, revealing why it demonstrates this unintuitive behavior.
Source:
https://phys.org/news/2020-05-tantalizing-clues-mysterious-material-conductor.html