****NON-TECHNICAL ABSTRACT**** This Small Grant for Exploratory Research enhances research opportunities for minority students at a Historically Black University. It will allow them to contribute to the discovery process, including experimental research and the exchange of ideas at the frontier of science. The project will attempt to elucidate whether an interpretation for the transport behavior of electrons in bismuth (Bi) nanowires when subjected to high magnetic fields is also valid for the recently observed behavior exhibited by charge carriers in bulk single crystal Bi. The observed effects in bulk Bi have been interpreted as being due to the electrons in bulk Bi behaving like electrons constrained to moving only in a thin layer (i.e., exhibiting the fractional charge of a collective quantum state of 2 dimensional electrons). The transport behavior in Bi nanowires has been interpreted as arising from electrons near the surface of the wire (i.e., the surface states). However, there are similarities between the magnetic field dependent transport measurements of Bi nanowires and bulk Bi. Low temperature electronic transport measurements in magnetic fields on bulk Bi will be performed. These measurements are designed to reveal the possible contributions from surface states and fractional charge. This timely project could be transformative in our understanding of Bi in the quantum limit and lead to future technologies.
This Small Grant for Exploratory Research enhances research opportunities for minority students at a Historically Black University. It will allow them to contribute to the discovery process, including experimental research and the exchange of ideas at the frontier of science. The project will attempt to elucidate whether surface states could explain the recently observed magneto-transport behavior in bulk Bi. Recent experimental studies of the Nernst effect and Hall effect of bulk Bi in the quantum limit (magnetic fields larger than 9 Tesla) have been interpreted in terms of charge fractionalization, an unusual collective quantum state seen only in two-dimensional electron gases. Absorption peaks with the same Shubnikov-deHaas period of 0.03/T have been observed in the magnetoresistance and thermopower of Bi nanowires both below and above the quantum limit of 9 T. In this case an interpretation in terms of surface states related to a spin-orbit surface interaction was proposed. Measurements of the magnetoresistance and Hall effect of thin samples of bulk single-crystal bismuth in magnetic fields up to 45 T will be performed. These measurements are designed to reveal possible contributions by surface states and fractional charge, allow evaluation of their properties such as effective masses, and permit evaluation of the relative importance of surface effects and electronic transport by bulk-like electrons and holes in bulk Bi. This timely project could be transformative in our understanding of Bi in the quantum limit and lead to future technologies.
