Structural Changes and the Nature of Superconductivity in Rare-earth Doped CaFe2As2
| dc.contributor.advisor | Paglione, Johnpierre | en_US |
| dc.contributor.author | Drye, Tyler Brunson | en_US |
| dc.contributor.department | Chemical Physics | en_US |
| dc.contributor.publisher | Digital Repository at the University of Maryland | en_US |
| dc.contributor.publisher | University of Maryland (College Park, Md.) | en_US |
| dc.date.accessioned | 2015-02-07T06:31:13Z | |
| dc.date.available | 2015-02-07T06:31:13Z | |
| dc.date.issued | 2014 | en_US |
| dc.description.abstract | Chemical substitution into iron-pnictide parent compounds (e.g. AFe<sub>2<\sub>As<sub>2<\sub> where A=Ba, Sr, or Ca) has proven to be an effective means to induce bulk high-temperature superconductivity in these systems. By doping CaFe<sub>2<\sub>As<sub>2<\sub> with rare-earth lanthanides (La, Ce, Pr, and Nd), we have observed a 47 K superconducting phase coexisting with a lattice distorting “collapse” transition. Both of these effects have important ramifications: the collapse transition occurs when interlayer As atoms form a bond, shrinking the <italic>c-axis<\italic> lattice constant and simultaneously quenching the iron magnetic moment. This transition is further explored in context of a similar system, Sr-doped BaNi<sub>2<\sub>As<sub>2<\sub>. The superconducting phase, given the right combination of conditions, appears with a critical temperature as high as 49 K, but always in a very small volume of the sample (as determined by shielding effects). This has led to interesting theories about the nature of this superconductivity. A recently posited idea of “interfacial superconductivity” has been ruled out by our tests. Additionally, increasing the concentration of rare-earth atoms does not increase the superconducting volume fraction, but, in fact lowers the transition temperature, excluding the hypothesis that rare-earth defects are responsible for the minority superconducting phase. New pressure measurements have shown that the superconducting phase is stabilized when antiferromagnetic order is fully suppressed. | en_US |
| dc.identifier | https://doi.org/10.13016/M2T31H | |
| dc.identifier.uri | http://hdl.handle.net/1903/16255 | |
| dc.language.iso | en | en_US |
| dc.subject.pqcontrolled | Condensed matter physics | en_US |
| dc.subject.pqcontrolled | Inorganic chemistry | en_US |
| dc.subject.pqcontrolled | Materials Science | en_US |
| dc.subject.pquncontrolled | CaFe2As2 | en_US |
| dc.subject.pquncontrolled | Iron Pnictides | en_US |
| dc.subject.pquncontrolled | iron superconductor | en_US |
| dc.subject.pquncontrolled | structural collapse | en_US |
| dc.title | Structural Changes and the Nature of Superconductivity in Rare-earth Doped CaFe2As2 | en_US |
| dc.type | Dissertation | en_US |
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