Speaker: Marek Kolmer

Host: Chunhui Chen

Title: Development of experimental techniques based on scanning tunneling microscopy for characterization of low-dimensional materials

Abstract:

The invention of scanning tunneling microscopy (STM) revolutionized experimental condensed matter physics, enabling direct access to real-space measurements on scales that reach single atoms and molecules on solid surfaces. The STM working principle is based on the precise control of the junction between the tip apex and a surface atomic plane. Once operated under ultra-high vacuum conditions and cryogenic temperatures, this technique provides unique capabilities for atomically precise mapping of local topography, the distribution of electronic density of states, and even the manipulation of single atoms or molecules into precise locations. Here, I will present our recent developments in STM-based experimental techniques and their applications to the synthesis and characterization of low-dimensional materials. I will discuss atomic-scale manipulation of matter using STM, specifically our recent work on manipulating buried graphene interfaces with an electric field under the STM tip. I will also show our spectroscopic methodology developments. First, I will introduce a two-probe STM-based spectroscopy to access transport properties at the atomic scale. And finally, I will present our recent work on STM spectroscopy operating in the high-bias voltage regime, which enables a systematic study of high-energy electronic states, as illustrated by the example of interface states in epitaxial graphene heterostructures.