Abstract
   Structural superlubricity is a physical state where friction between two surfaces in relative motion nearly vanishes, in the absence of any lubricants, purely as a result of structural incommensurability at the interface. Research on this intriguing phenomenon has accelerated rapidly in the past decade, with the discovery and investigation of new superlubric material systems by a few research groups around the world. These research advances have bolstered hopes for structural superlubricity to be applied in model mechanical systems, potentially revolutionizing their efficiency and longevity. However, many open questions remain regarding the physical limitations of structural superlubricity. In this thesis, we address the robustness of structural superlubricity with respect to rotations, environmental contamination, and sliding speed. Our fundamental studies employ atomic force microscopy (AFM) to manipulate gold nano-islands on graphite under various conditions. In particular, we describe a novel lock-in-amplifier-based manipulation technique that allows for precise displacement of nano-islands while significantly increasing the reliability of acquired data. Results show that friction forces remain ultra- low (under 1 nN) at gold-graphite interfaces even under contaminated conditions, at high speeds, and with significant rotations involved.

Biography
   Wai Hnin Oo is a PhD candidate in Mechanical Engineering at UC Merced and a National Science Foundation (NSF) Graduate Research Fellow. She joined Baykara Lab in Fall 2019, soon after obtaining her B.S. in Mechanical Engineering from UC Irvine. At Baykara Lab, she studies fundamental aspects of structural superlubricity through AFM nanomanipulation experiments.

Zoom Link

https://ucmerced.zoom.us/j/859524