UC Berkeley

The isolation of single-layered graphene and transition metal dichalcogenides has prompted a large body of research on the novel properties and practical applications of layered materials. Of note are moiré materials: twisted or lattice-mismatched layers that form metastable structural beating patterns with twist-dependent properties. Such structures serve as convenient physical simulators that avoid the need to arduously synthesize a range of materials. Intercalation, wherein additional possibly spin-bearing ions are introduced within the van Der Waals gap, is of interest to additionally enable designer (magnetic) materials of a chosen crystal field and lattice symmetry. In both cases, the precise atomic structure drives key properties and requires careful investigation outside of the limiting assumptions of negligible atomic relaxation or configurational disorder. This dissertation will discuss the use and development of an electron microscopy technique to characterize structural relaxation in realistic (encapsulated and multi-layered) moiré materials and the application of modern electronic structure theory tools to predict intercalant ordering within select transition metal dichalcogenides.