Browsing by Author "Dorow, Chelsey"

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    Neutron Scattering Study of the High-Temperature Superconductor HgBa2CuO
    (2013-04-20) Dorow, Chelsey
    Superconductivity, a phenomenon in which materials exhibit zero electrical resistance when cooled below a characteristic transition temperature, Tc, was discovered over 100 years ago. It wasn’t until 1957 that a theory successfully described this phenomenon. Electrons are able to conduct with zero electrical resistance by binding into pairs, named Cooper pairs. In conventional superconductors (with Tc below ~30K), Cooper pairs are formed when the electrons interact with vibrations of the crystal lattice, phonons. For high-temperature superconductors, with Tc values ranging up to 130K, the pairing mechanism for Cooper pairs is yet to be understood. A primary goal in the study of high-temperature superconductivity is to determine this pairing mechanism and to further understand the magnetic and electronic phases of these materials. Neutron scattering was used to study magnetic excitations in the high-temperature superconductor HgBa2CuO4+δ (Hg1201). Such excitations are a candidate for the pairing mechanism. Hg1201 is of critical importance as it possesses one of the highest Tc values and is considered a model compound with a relatively simple structure.
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    Optimization of the Crystal Growth Process for the High-Temperature Superconductor HgBa2 CuO4+8
    (2012-04-18) Dorow, Chelsey
    HgBa2 CuO4+8(Hg1201)is of critical importance in the study of high-­temperature superconductivity as it possesses one of the highest Tc values and is considered a model compound with a relatively simple structure. Research on Hg1201, particularly in the area of neutron scattering, has been limited by the demanding crystal growth procedure. Neutron scattering has proven to be a useful tool as neutrons interact magnetically with crystals, allowing for the detection of magnetic excitations; magnetic properties in different phases of high-­Tc materials are thought to be linked to the mechanism for superconductivity. Preparing a sample suitable for neutron scattering involves an intensive growth effort, as the weak nature of the neutron scattering cross section requires large, high-­‐quality crystal samples. The growth process of Hg1201 was optimized, resulting in several crystal samples to be measured with neutron scattering.