Abstract: Different classes of quantum materials abound with rich correlated physics in the bulk form, such as superconductivity, magnetism and more recently, topological states; but many of them are virtually unexplored in the reduced-dimension structures. Specific classes of nanostructured quantum materials of great interest are 2D van der Waals (vdW) magnet and atomically-thin single chains of 1D vdW materials.

In the first part of my talk, I will introduce an environmentally stable 2-D vdW magnet, CrSBr, which allows us to explore its atomic structure by scanning transmission electron microscopy (STEM). I will then present an electron-beam irradiation method to manipulate the defect formation and consequently to design the spin texture in the material.

In the second part of my talk, I will present my recent efforts in isolation and study of a single chain of 1D vdW materials encapsulated within carbon and boron nitride nanotubes, by the combination of aberration-corrected S/TEM and density functional theory, exemplified by the discovery of torsional instability and helical structural wave in few-to-single chain of charge-density wave NbSe₃.