Abstract

This dissertation is broadly divided into two parts. The first part details the development and usage of an experimental apparatus to measure the dry nanofriction for a well-defined interface at high sliding speeds. I leverage the sensitivity of a quartz crystal microbalance (QCM) to determine the drag coefficient of an ensemble of gold nanocrystals sliding on graphene at speeds up to 11 cm/s. I discuss the theories of velocity-dependent friction, especially at high sliding speeds, and QCM modeling. I also discuss our synthesis protocols for graphene and molybdenum disulfide, as well as our protocol for fabricating a clean, graphene-laminated QCM device and nanocrystal ensemble. The design and fabrication of our QCM oscillator circuit is presented in detail. The quantitatively-measured the drag coefficient is compared against molecular dynamics simulations at both low and high sliding speeds. We show evidence of a predicted ultra-low friction regime and find that the interaction energy between gold nanocrystals and graphene is lower than previously assumed. In the second part of this dissertation, I detail the band structure measurement of a novel semimetal using scanning tunneling microscopy. In particular, I measured the energy-dependence of quasiparticle interference patterns at the surface of zirconium silicon sulfide (ZrSiS), a topological nodal line semimetal whose charge carrier quasiparticles possess a pseudospin degree of freedom. The aims of this study were to (1) discover the shape of the band structure above the Fermi level along a high-symmetry direction, (2) discover the energetic location of the line node in the same high-symmetry direction, and (3) discover the selection rules for k transitions. This study confirms the predicted linearity in E(k) of the band structure above the Fermi level. Additionally, we observe an energy-dependent mechanism for pseudospin scattering. This study also provides the first experimentally-derived estimation of the line node position in E(k).

Notes

If this is your thesis or dissertation, and want to learn how to access it or for more information about readership statistics, contact us at STARS@ucf.edu

Graduation Date

2018

Semester

Summer

Advisor

Ishigami, Masahiro

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Degree Program

Physics

Format

application/pdf

Identifier

CFE0007218

URL

http://purl.fcla.edu/fcla/etd/CFE0007218

Language

English

Release Date

August 2023

Length of Campus-only Access

5 years

Access Status

Doctoral Dissertation (Open Access)

Included in

Physics Commons

Share

COinS