{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/22402"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/22402","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Heat capacity measurements of yttrium barium(2)copper(3)oxygen(7-delta) near T(c): Fluctuation effects in a bulk superconductor","abstract":"\"High-resolution ac heat capacity measurements of YBa$\\sb2$Cu$\\sb3$O$\\sb{\\rm 7-\\delta}$ near the critical temperature are reported and discussed. The samples are high-quality single crystals, several of which display untwinned regions making up at least 50% of the sample mass. The heat capacity data show a cusp-like anomaly instead of the discontinuous step observed in \"\"classic\"\" superconductors. This divergence is indicative of the presence of fluctuation contributions and is due to the exceptionally short Ginzburg-Landau coherence length of this material. Because there is considerable uncertainty in the temperature of cross-over from mean-field to critical behavior, the zero-field heat capacity data are analyzed both as a lowest-order correction to mean-field BCS theory (the Gaussian approximation) and in terms of true critical behavior. The analysis shows that the data are best described within the Gaussian approximation as three-dimensional fluctuations of a two-component order parameter, but the results do not rule out a more complicated order parameter or a logarithmic (critical) divergence. The underlying BCS step indicates strong-coupling behavior.\"","abstract_html":"&quot;High-resolution ac heat capacity measurements of YBa$\\sb2$Cu$\\sb3$O<span class=\"etd-inline-math\">\\sb{\\rm 7-&delta;}</span> near the critical temperature are reported and discussed. The samples are high-quality single crystals, several of which display untwinned regions making up at least 50% of the sample mass. The heat capacity data show a cusp-like anomaly instead of the discontinuous step observed in &quot;&quot;classic&quot;&quot; superconductors. This divergence is indicative of the presence of fluctuation contributions and is due to the exceptionally short Ginzburg-Landau coherence length of this material. Because there is considerable uncertainty in the temperature of cross-over from mean-field to critical behavior, the zero-field heat capacity data are analyzed both as a lowest-order correction to mean-field BCS theory (the Gaussian approximation) and in terms of true critical behavior. The analysis shows that the data are best described within the Gaussian approximation as three-dimensional fluctuations of a two-component order parameter, but the results do not rule out a more complicated order parameter or a logarithmic (critical) divergence. The underlying BCS step indicates strong-coupling behavior.&quot;","abstract_has_math":true,"creators":["Inderhees, Sue Ellen"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Salamon, Myron B."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T13:38:41Z","date_published":"2011-05-07T13:38:41Z","updated_at":"2026-07-22T22:25:19Z","subjects":["Physics, Condensed Matter"],"languages":["eng"],"rights":["Copyright 1990 Inderhees, Sue Ellen"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9114278","(UMI)AAI9114278"],"render_values":[{"text":"AAI9114278","href":null,"code":true},{"text":"(UMI)AAI9114278","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/22402","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Salamon, Myron B."]},{"key":"dc:creator","label":"Author","values":["Inderhees, Sue Ellen"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T13:38:41Z","10000-01-01","1990"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics, Condensed Matter"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1990 Inderhees, Sue Ellen"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9114278","(UMI)AAI9114278","http://hdl.handle.net/2142/22402"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["\"High-resolution ac heat capacity measurements of YBa$\\sb2$Cu$\\sb3$O$\\sb{\\rm 7-\\delta}$ near the critical temperature are reported and discussed. The samples are high-quality single crystals, several of which display untwinned regions making up at least 50% of the sample mass. The heat capacity data show a cusp-like anomaly instead of the discontinuous step observed in \"\"classic\"\" superconductors. This divergence is indicative of the presence of fluctuation contributions and is due to the exceptionally short Ginzburg-Landau coherence length of this material. Because there is considerable uncertainty in the temperature of cross-over from mean-field to critical behavior, the zero-field heat capacity data are analyzed both as a lowest-order correction to mean-field BCS theory (the Gaussian approximation) and in terms of true critical behavior. The analysis shows that the data are best described within the Gaussian approximation as three-dimensional fluctuations of a two-component order parameter, but the results do not rule out a more complicated order parameter or a logarithmic (critical) divergence. The underlying BCS step indicates strong-coupling behavior.\"","Application of a magnetic field broadens and suppresses the heat capacity transition, with no apparent shift in the onset of superconductivity, and with the effects more pronounced for fields applied parallel to the c-axis than for fields in the ab-plane. We find this behavior cannot be explained in terms mean-field theory. Rather, the anisotropic broadening and suppression may be understood in the context of critical finite-size scaling, since the length scale of the fluctuations is essentially restricted to values less than the lowest-order Landau radius in directions perpendicular to the applied field.","Made available in DSpace on 2011-05-07T13:38:41Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9114278.pdf: 4733854 bytes, checksum: 0ba701f834da66673b0c5e7a50398c19 (MD5) Previous issue date: 1990","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:57:22Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:26:54-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"]},{"key":"dc:title","label":"Title","values":["Heat capacity measurements of yttrium barium(2)copper(3)oxygen(7-delta) near T(c): Fluctuation effects in a bulk superconductor"]}]}],"canonical_facts":{"dc:contributor":["Salamon, Myron B."],"dc:creator":["Inderhees, Sue Ellen"],"dc:date":["2011-05-07T13:38:41Z","10000-01-01","1990"],"dc:description":["\"High-resolution ac heat capacity measurements of YBa$\\sb2$Cu$\\sb3$O$\\sb{\\rm 7-\\delta}$ near the critical temperature are reported and discussed. The samples are high-quality single crystals, several of which display untwinned regions making up at least 50% of the sample mass. The heat capacity data show a cusp-like anomaly instead of the discontinuous step observed in \"\"classic\"\" superconductors. This divergence is indicative of the presence of fluctuation contributions and is due to the exceptionally short Ginzburg-Landau coherence length of this material. Because there is considerable uncertainty in the temperature of cross-over from mean-field to critical behavior, the zero-field heat capacity data are analyzed both as a lowest-order correction to mean-field BCS theory (the Gaussian approximation) and in terms of true critical behavior. The analysis shows that the data are best described within the Gaussian approximation as three-dimensional fluctuations of a two-component order parameter, but the results do not rule out a more complicated order parameter or a logarithmic (critical) divergence. The underlying BCS step indicates strong-coupling behavior.\"","Application of a magnetic field broadens and suppresses the heat capacity transition, with no apparent shift in the onset of superconductivity, and with the effects more pronounced for fields applied parallel to the c-axis than for fields in the ab-plane. We find this behavior cannot be explained in terms mean-field theory. Rather, the anisotropic broadening and suppression may be understood in the context of critical finite-size scaling, since the length scale of the fluctuations is essentially restricted to values less than the lowest-order Landau radius in directions perpendicular to the applied field.","Made available in DSpace on 2011-05-07T13:38:41Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9114278.pdf: 4733854 bytes, checksum: 0ba701f834da66673b0c5e7a50398c19 (MD5) Previous issue date: 1990","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:57:22Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:26:54-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"],"dc:identifier":["AAI9114278","(UMI)AAI9114278","http://hdl.handle.net/2142/22402"],"dc:language":["eng"],"dc:rights":["Copyright 1990 Inderhees, Sue Ellen"],"dc:subject":["Physics, Condensed Matter"],"dc:title":["Heat capacity measurements of yttrium barium(2)copper(3)oxygen(7-delta) near T(c): Fluctuation effects in a bulk superconductor"],"dc:type":["text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:19Z"}