Physics Commons^™

Two-Dimensional Bloch Electrons In Electric And Magnetic Fields, Edward Aris Diaz Fajardo

Graduate Research Theses & Dissertations

Due to their extraordinary mechanical, and fascinating electronic properties, atomically flat two-dimensional materials are attractive avenues in the search for new and interesting physical phenomena. Symmetry is a powerful tool in studying the dynamics of Bloch electrons in these crystalline solids. Here, using a tight binding description, a systematic scheme is developed to derive the symmetry labels, called irreducible representations (IRs), characterizing the Bloch eigenstates in a crystal, including an extensive discussion on the possibility that these IRs are not always unique. This theory is illustrated using monolayer MoS$_2$ and few-layer graphene as examples. Using this symmetry analysis in conjunction …

Many-Particle Systems, 7, David Peak

Many Particles

Electronic energy bands in crystalline solids: The finite well model

Previously, we have considered the “conduction electrons” in a metal as if they were an ideal gas in a 3D infinite well. What allows us to do that? A crystalline solid consists of a periodic array of atoms, packed so close to one another that “flow” (long range relative motion of groups of atoms) is essentially impossible. It is useful to think of a solid as a giant (rigid) molecule. The periodic structure of the atoms has profound consequences for the behavior of the solid’s electrons. While, in detail, the …

Copper Doping Of Zno Crystals By Transmutation Of 64Zn To 65Cu: An Electron Paramagnetic Resonance And Gamma Spectroscopy Study, Matthew C. Recker, John W. Mcclory, Maurio S. Holston, Eric M. Golden, Nancy C. Giles, Larry E. Halliburton

Faculty Publications

Transmutation of ⁶⁴Zn to ⁶⁵Cu has been observed in a ZnO crystal irradiated with neutrons. The crystal was characterized with electron paramagnetic resonance (EPR) before and after the irradiation and with gamma spectroscopy after the irradiation. Major features in the gamma spectrum of the neutron-irradiated crystal included the primary 1115.5 keV gamma ray from the ⁶⁵Zn decay and the positron annihilation peak at 511 keV. Their presence confirmed the successful transmutation of ⁶⁴Zn nuclei to ⁶⁵Cu. Additional direct evidence for transmutation was obtained from the EPR of Cu²⁺ ions (where ⁶³Cu and ^{65 …}

Neutral Nitrogen Acceptors In Zno: The 67Zn Hyperfine Interactions, Eric M. Golden, S. M. Evans, Larry E. Halliburton, Nancy C. Giles

Faculty Publications

Electron paramagnetic resonance (EPR) is used to characterize the ⁶⁷Zn hyperfine interactions associated with neutral nitrogen acceptors in zinc oxide. Data are obtained from an n-type bulk crystal grown by the seeded chemical vapor transport method. Singly ionized nitrogen acceptors (N⁻) initially present in the crystal are converted to their paramagnetic neutral charge state (N⁰) during exposure at low temperature to 442 or 633 nm laser light. The EPR signals from these N⁰ acceptors are best observed near 5 K. Nitrogen substitutes for oxygen ions and has four nearest-neighbor cations. The zinc ion …