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Full-Text Articles in Physics
Disorder Influences The Quantum Critical Transport At A Superconductor-To-Insulator Transition, H Q. Nguyen, Shawna M. Hollen, J M. Valles Jr., J Shainline, J. M. Xu
Disorder Influences The Quantum Critical Transport At A Superconductor-To-Insulator Transition, H Q. Nguyen, Shawna M. Hollen, J M. Valles Jr., J Shainline, J. M. Xu
Physics & Astronomy
We isolated flux disorder effects on the transport at the critical point of the quantum magnetic field tuned superconductor-to-insulator transition (BSIT). The experiments employed films patterned into geometrically disordered hexagonal arrays. Spatial variations in the flux per unit cell, which grow in a perpendicular magnetic field, constitute flux disorder. The growth of flux disorder with magnetic field limited the number of BSITs exhibited by a single film due to flux matching effects. The critical metallic resistance at successive BSITs grew with flux disorder contrary to predictions of its universality. These results open the door for controlled studies of disorder effects …
Modification Of Electronic Surface States By Graphene Islands On Cu(111), Shawna M. Hollen, G A. Gambrel, S J. Tjung, N M. Santagata, Ezekiel Johnston-Halperin, Jay A. Gupta
Modification Of Electronic Surface States By Graphene Islands On Cu(111), Shawna M. Hollen, G A. Gambrel, S J. Tjung, N M. Santagata, Ezekiel Johnston-Halperin, Jay A. Gupta
Physics & Astronomy
We present a study of graphene/substrate interactions on ultrahigh-vacuum-grown graphene islands with minimal surface contamination using in situ low-temperature scanning tunneling microscopy. We compare the physical and electronic structure of the sample surface with atomic spatial resolution on graphene islands versus regions of bare Cu(111) substrate. We find that the Rydberg-like series of image potential states is shifted toward lower energy over the graphene islands relative to Cu(111), indicating a decrease in the local work function, and the resonances have a much smaller linewidth, indicating reduced coupling to the bulk. In addition, we show the dispersion of the occupied Cu(111) …
Transport In Thin Insulating Films Close To The Boson-Fermion Crossover, J C. Joy, X Zhang, Shawna M. Hollen, C Zhao, G. E. Fernandes, J. M. Xu, J M. Valles Jr.
Transport In Thin Insulating Films Close To The Boson-Fermion Crossover, J C. Joy, X Zhang, Shawna M. Hollen, C Zhao, G. E. Fernandes, J. M. Xu, J M. Valles Jr.
Physics & Astronomy
No abstract provided.
Scanning Tunneling Microscopy Studies Of Graphene And Hydrogenated Graphene On Cu, Shawna M. Hollen, G A. Gambrel, S J. Tjung, N M. Santagata, Ezekiel Johnston-Halperin, Jay A. Gupta
Scanning Tunneling Microscopy Studies Of Graphene And Hydrogenated Graphene On Cu, Shawna M. Hollen, G A. Gambrel, S J. Tjung, N M. Santagata, Ezekiel Johnston-Halperin, Jay A. Gupta
Physics & Astronomy
Because of the innate sensitivity of 2D material surfaces, it is increasingly important to understand and characterize surface functionalization and interactions with environmental elements, such as substrate, metallic contacts, and adatoms. We developed a method for reproducible, epitaxial growth of pristine graphene islands on Cu(111) in UHV and use scanning tunneling microscopy and spectroscopy (STM) to study the interaction of these graphene islands with the Cu substrate. Tunneling spectroscopy measurements of the electronic surface states over the graphene islands indicate a lower local work function, decreased coupling to bulk Cu states, and a decreased electron effective mass. Additionally, we developed …
How Accurate Are Physics Students In Evaluating Changes In Their Understanding?, Therese Claire, Tija L. Tippett, Andrew Boudreaux
How Accurate Are Physics Students In Evaluating Changes In Their Understanding?, Therese Claire, Tija L. Tippett, Andrew Boudreaux
Physics & Astronomy
An assessment question involving Newton’s 2nd law was administered in a physics course for preservice elementary teachers before and again after instruction. The posttest included a prompt asking students to describe the specific ways their thinking changed. Student reasoning was coded for physics content accuracy; many students exhibited changes from primitive, experientially-based reasoning to more formal reasoning. Students' self-reported reflections were then compared to the differences in the pre- and posttest codes. We find that many students do not identify substantive changes in their reasoning, while other students reflect at only a surface level. We also find that some students …