{"id":{"repo_id":"maryland","oai_identifier":"oai:drum.lib.umd.edu:1903/16508"},"canonical_url":"https://search.dev.ndltd.org/etd/maryland/oai:drum.lib.umd.edu:1903/16508","repository":{"repo_id":"maryland","name":"University of Maryland","base_url":"https://api.drum.lib.umd.edu/server/oai/request"},"display":{"title":"Investigation of Iron-Based and Topological Superconductors via Point-Contact Spectroscopy","abstract":"I report results of point-contact spectroscopy (PCS) measurements preformed on a variety of superconductors which are predicted to exhibit unconventional Cooper pairing mechanisms. Point-contact spectra of the iron pnictide BaFe_{1-x}$Pt$_x$As$_2$ are consistent with a two-gap isotropic s-wave model. This conclusion is supported by previously published results from thermal conductivity, angle-resolved photoemission spectroscopy (ARPES), and Raman spectroscopy, which confirm a lack of nodes in the order parameter and the presence of a gap of magnitude 3 meV. Conductivity spectra were also measured for the half-Heusler materials YPtBi and LuPdBi using the soft point contact method. I argue that the repeated observation of a single peak in $dI/dV$ at zero bias is not consistent with a conventional $s$-wave model. Based on attempts to fit my data to the Blonder-Tinkham-Klapwijk theory and comparison to previous experimental and theoretical work, I conclude that my results are most consistent with a model of triplet Cooper pairs and an order parameter with an odd-parity component.","abstract_html":"I report results of point-contact spectroscopy (PCS) measurements preformed on a variety of superconductors which are predicted to exhibit unconventional Cooper pairing mechanisms. Point-contact spectra of the iron pnictide BaFe_{1-x}$Pt$_x$As$_2$ are consistent with a two-gap isotropic s-wave model. This conclusion is supported by previously published results from thermal conductivity, angle-resolved photoemission spectroscopy (ARPES), and Raman spectroscopy, which confirm a lack of nodes in the order parameter and the presence of a gap of magnitude 3 meV. Conductivity spectra were also measured for the half-Heusler materials YPtBi and LuPdBi using the soft point contact method. I argue that the repeated observation of a single peak in $dI/dV$ at zero bias is not consistent with a conventional $s$-wave model. Based on attempts to fit my data to the Blonder-Tinkham-Klapwijk theory and comparison to previous experimental and theoretical work, I conclude that my results are most consistent with a model of triplet Cooper pairs and an order parameter with an odd-parity component.","abstract_has_math":true,"creators":["Ziemak, Steven Joseph"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Chemical Physics","school":null,"contributors":[],"advisors":["Paglione, Johnpierre"],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015","date_published":"2015","updated_at":"2026-07-24T03:02:25Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://doi.org/10.13016/M2CP80"],"render_values":[{"text":"https://doi.org/10.13016/M2CP80","href":"https://doi.org/10.13016/M2CP80","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/1903/16508","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Paglione, Johnpierre"]},{"key":"dc:contributor.department","label":"Department","values":["Chemical Physics"]},{"key":"dc:creator","label":"Author","values":["Ziemak, Steven Joseph"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2015-06-25T05:49:34Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2015-06-25T05:49:34Z"]},{"key":"dc:date.issued","label":"Date","values":["2015"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://doi.org/10.13016/M2CP80"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1903/16508"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["I report results of point-contact spectroscopy (PCS) measurements preformed on a variety of superconductors which are predicted to exhibit unconventional Cooper pairing mechanisms. Point-contact spectra of the iron pnictide BaFe_{1-x}$Pt$_x$As$_2$ are consistent with a two-gap isotropic s-wave model. This conclusion is supported by previously published results from thermal conductivity, angle-resolved photoemission spectroscopy (ARPES), and Raman spectroscopy, which confirm a lack of nodes in the order parameter and the presence of a gap of magnitude 3 meV. Conductivity spectra were also measured for the half-Heusler materials YPtBi and LuPdBi using the soft point contact method. I argue that the repeated observation of a single peak in $dI/dV$ at zero bias is not consistent with a conventional $s$-wave model. Based on attempts to fit my data to the Blonder-Tinkham-Klapwijk theory and comparison to previous experimental and theoretical work, I conclude that my results are most consistent with a model of triplet Cooper pairs and an order parameter with an odd-parity component."]},{"key":"dc:title","label":"Title","values":["Investigation of Iron-Based and Topological Superconductors via Point-Contact Spectroscopy"]}]}],"canonical_facts":{"dc:contributor.advisor":["Paglione, Johnpierre"],"dc:contributor.department":["Chemical Physics"],"dc:creator":["Ziemak, Steven Joseph"],"dc:date.accessioned":["2015-06-25T05:49:34Z"],"dc:date.available":["2015-06-25T05:49:34Z"],"dc:date.issued":["2015"],"dc:description.abstract":["I report results of point-contact spectroscopy (PCS) measurements preformed on a variety of superconductors which are predicted to exhibit unconventional Cooper pairing mechanisms. Point-contact spectra of the iron pnictide BaFe_{1-x}$Pt$_x$As$_2$ are consistent with a two-gap isotropic s-wave model. This conclusion is supported by previously published results from thermal conductivity, angle-resolved photoemission spectroscopy (ARPES), and Raman spectroscopy, which confirm a lack of nodes in the order parameter and the presence of a gap of magnitude 3 meV. Conductivity spectra were also measured for the half-Heusler materials YPtBi and LuPdBi using the soft point contact method. I argue that the repeated observation of a single peak in $dI/dV$ at zero bias is not consistent with a conventional $s$-wave model. Based on attempts to fit my data to the Blonder-Tinkham-Klapwijk theory and comparison to previous experimental and theoretical work, I conclude that my results are most consistent with a model of triplet Cooper pairs and an order parameter with an odd-parity component."],"dc:identifier":["https://doi.org/10.13016/M2CP80"],"dc:identifier.uri":["http://hdl.handle.net/1903/16508"],"dc:language.iso":["en"],"dc:title":["Investigation of Iron-Based and Topological Superconductors via Point-Contact Spectroscopy"],"dc:type":["Dissertation"]},"updated_at":"2026-07-24T03:02:25Z"}