{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/30727"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/30727","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Fluctuation conductivity from charge density waves in pseudo-one-dimensional systems","abstract":"This thesis examines theoretically the Fröhlich conductivity model, which describes a charge-density-wave phenomenon which can lead to enhanced electrical conductivity in pseudo-one-dimensional systems. The experimental facts concerning pseudo-one-dimensional systems which may illustrate aspects of the Fröhlich mechanism are reviewed. The physical basis of the Fröhlich model is discussed in detail and is extended by the new suggestion that the important Fröhlich mode frequencies are less than the Kohn anomaly frequency. A phenomenological formulation of the free energy is used to calculate the fluctuation electrical conductivity (paraconductivity) at temperatures where the fluctuations are still mobile. The result gives values which are somewhat small to account for the largest experimental results. The fluctuation thermal conductivity is calculated similarly, and its ratio to the paraconductivity is found to be suppressed, very much as in the BCS model. A microscopic model is introduced through the formulation of the Fröhlich collective mode propagator, approximations to which are examined for deficiencies. An approximation to the propagator is used to calculate diagrammatically the paraconductivity. An attempt is made to resolve disagreement in the literature regarding this calculation, and the correspondence of the mic,oscopic and phenomenological results is discussed. The use of mean-field theory in one dimension limits the validity of these calculations to several degrees above the transition temperature.","abstract_html":"This thesis examines theoretically the Fröhlich conductivity model, which describes a charge-density-wave phenomenon which can lead to enhanced electrical conductivity in pseudo-one-dimensional systems. The experimental facts concerning pseudo-one-dimensional systems which may illustrate aspects of the Fröhlich mechanism are reviewed. The physical basis of the Fröhlich model is discussed in detail and is extended by the new suggestion that the important Fröhlich mode frequencies are less than the Kohn anomaly frequency. A phenomenological formulation of the free energy is used to calculate the fluctuation electrical conductivity (paraconductivity) at temperatures where the fluctuations are still mobile. The result gives values which are somewhat small to account for the largest experimental results. The fluctuation thermal conductivity is calculated similarly, and its ratio to the paraconductivity is found to be suppressed, very much as in the BCS model. A microscopic model is introduced through the formulation of the Fröhlich collective mode propagator, approximations to which are examined for deficiencies. An approximation to the propagator is used to calculate diagrammatically the paraconductivity. An attempt is made to resolve disagreement in the literature regarding this calculation, and the correspondence of the mic,oscopic and phenomenological results is discussed. The use of mean-field theory in one dimension limits the validity of these calculations to several degrees above the transition temperature.","abstract_has_math":false,"creators":["Bray, James William"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Bardeen, John"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-04-22T17:02:18Z","date_published":"2012-04-22T17:02:18Z","updated_at":"2026-07-22T22:25:29Z","subjects":["fluctuation conductivity","charge density waves","pseudo-one-dimensional systems","Fröhlich conductivity model"],"languages":["en"],"rights":["Copyright 1974 James W. Bray"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["2638819"],"render_values":[{"text":"2638819","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/30727","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Bardeen, John"]},{"key":"dc:creator","label":"Author","values":["Bray, James William"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-04-22T17:02:18Z","10000-01-01","1974"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation / Thesis","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":["fluctuation conductivity","charge density waves","pseudo-one-dimensional systems","Fröhlich conductivity model"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1974 James W. 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The result gives values which are somewhat small to account for the largest experimental results. The fluctuation thermal conductivity is calculated similarly, and its ratio to the paraconductivity is found to be suppressed, very much as in the BCS model. A microscopic model is introduced through the formulation of the Fröhlich collective mode propagator, approximations to which are examined for deficiencies. An approximation to the propagator is used to calculate diagrammatically the paraconductivity. An attempt is made to resolve disagreement in the literature regarding this calculation, and the correspondence of the mic,oscopic and phenomenological results is discussed. The use of mean-field theory in one dimension limits the validity of these calculations to several degrees above the transition temperature.","Submitted by William Weathers (weathrs2@illinois.edu) on 2012-04-22T17:02:18Z No. of bitstreams: 1 1974_bray.pdf: 2573898 bytes, checksum: fb18f2668588bf10c508822b85cb0cd4 (MD5)","Made available in DSpace on 2012-04-22T17:02:18Z (GMT). No. of bitstreams: 1 1974_bray.pdf: 2573898 bytes, checksum: fb18f2668588bf10c508822b85cb0cd4 (MD5) Previous issue date: 1974","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by William Weathers (weathrs2@illinois.edu) on 2012-04-22T17:02:18Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:33:46-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis","Thesis","U of I Only"]},{"key":"dc:title","label":"Title","values":["Fluctuation conductivity from charge density waves in pseudo-one-dimensional systems"]}]}],"canonical_facts":{"dc:contributor":["Bardeen, John"],"dc:creator":["Bray, James William"],"dc:date":["2012-04-22T17:02:18Z","10000-01-01","1974"],"dc:description":["This thesis examines theoretically the Fröhlich conductivity model, which describes a charge-density-wave phenomenon which can lead to enhanced electrical conductivity in pseudo-one-dimensional systems. The experimental facts concerning pseudo-one-dimensional systems which may illustrate aspects of the Fröhlich mechanism are reviewed. The physical basis of the Fröhlich model is discussed in detail and is extended by the new suggestion that the important Fröhlich mode frequencies are less than the Kohn anomaly frequency. A phenomenological formulation of the free energy is used to calculate the fluctuation electrical conductivity (paraconductivity) at temperatures where the fluctuations are still mobile. The result gives values which are somewhat small to account for the largest experimental results. The fluctuation thermal conductivity is calculated similarly, and its ratio to the paraconductivity is found to be suppressed, very much as in the BCS model. A microscopic model is introduced through the formulation of the Fröhlich collective mode propagator, approximations to which are examined for deficiencies. An approximation to the propagator is used to calculate diagrammatically the paraconductivity. An attempt is made to resolve disagreement in the literature regarding this calculation, and the correspondence of the mic,oscopic and phenomenological results is discussed. The use of mean-field theory in one dimension limits the validity of these calculations to several degrees above the transition temperature.","Submitted by William Weathers (weathrs2@illinois.edu) on 2012-04-22T17:02:18Z No. of bitstreams: 1 1974_bray.pdf: 2573898 bytes, checksum: fb18f2668588bf10c508822b85cb0cd4 (MD5)","Made available in DSpace on 2012-04-22T17:02:18Z (GMT). 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Bray"],"dc:subject":["fluctuation conductivity","charge density waves","pseudo-one-dimensional systems","Fröhlich conductivity model"],"dc:title":["Fluctuation conductivity from charge density waves in pseudo-one-dimensional systems"],"dc:type":["Dissertation / Thesis","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":"2026-07-22T22:25:29Z"}