(Invited) Custom Low-Dimensional Material Systems Explored at the Atomic Scale

Abstract

Innovative technologies have a history of capitalizing on the discovery of new physical phenomena, often at the confluence of advances in material characterization techniques and innovations in design and controlled synthesis of high-quality materials. Pioneered by the discovery of graphene, atomically thin materials (2D materials) hold the promise for realizing physical systems with distinct properties, previously inaccessible. In this talk I will describe experiments that seek to uncover the novel physical phenomena in 2D materials by using scanning tunneling microscopy and spectroscopy (STM/STS) and supporting spectroscopic techniques. Firstly, I will discuss the 1T polymorph of TaS2, which has one of the richest phase diagrams among the layered transition metal dichalcogenides and address the question of crossover from bulk to few layers. Secondly, I will describe atomic-scale characterization of the in-plane anisotropic semiconductor ReS2. We demonstrate that rhenium atoms form diamond-shaped clusters, organized in disjointed chains, and characterize the semiconducting electronic band gap by STS. By spatially mapping the local density of states around defects in ReS2, we explore their origin and electrostatic nature.