{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/31256"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/31256","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Mesoscopic noise probe of an inhomogeneous colossal magnetoresistance phase","abstract":"Epitaxial single-crystal films of La2; 3Ca1; 3Mn03 exhibit large discrete equilibrium resistance fluctuations in the region of phase space where colossal magnetoresistance effects are strongest. The fluctuators' dependence on magnetic field indicates that the resistance steps represent small regions of material fluctuating between a paramagnetic insulating phase and a ferromagnetic conducting phase. The dependences of Boltzmann factors on field and temperature give the magnetic moment and entropy differences between the states, providing quantitative thermodynamic information about the locally homogeneous CMR phase transition in an otherwise inhomogeneous sample. The size of the discrete resistance fluctuations reveals a very inhomogeneous current density. The temperature dependence of some fluctuators provides evidence for thermodynamic effects which stabilize the mixed phase. A separate experiment on the spin glass CuMnAu investigates the effect of strong local anisotropy on spin glass dynamics. The result demonstrates that altering the symmetry of a spin glass Hamiltonian on the scale of the two-spin interaction has a strong qualitative effect on the low-energy frozen spin glass state space.","abstract_html":"Epitaxial single-crystal films of La2; 3Ca1; 3Mn03 exhibit large discrete equilibrium resistance fluctuations in the region of phase space where colossal magnetoresistance effects are strongest. The fluctuators' dependence on magnetic field indicates that the resistance steps represent small regions of material fluctuating between a paramagnetic insulating phase and a ferromagnetic conducting phase. The dependences of Boltzmann factors on field and temperature give the magnetic moment and entropy differences between the states, providing quantitative thermodynamic information about the locally homogeneous CMR phase transition in an otherwise inhomogeneous sample. The size of the discrete resistance fluctuations reveals a very inhomogeneous current density. The temperature dependence of some fluctuators provides evidence for thermodynamic effects which stabilize the mixed phase. A separate experiment on the spin glass CuMnAu investigates the effect of strong local anisotropy on spin glass dynamics. The result demonstrates that altering the symmetry of a spin glass Hamiltonian on the scale of the two-spin interaction has a strong qualitative effect on the low-energy frozen spin glass state space.","abstract_has_math":false,"creators":["Merithew, Robert David"],"institution":null,"degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Weissman, Michael B."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-05-29T18:31:44Z","date_published":"2012-05-29T18:31:44Z","updated_at":"2026-07-22T22:25:30Z","subjects":["epitaxial single-crystal films"],"languages":["en"],"rights":["©2000 Merithew"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["4340048"],"render_values":[{"text":"4340048","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/31256","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Weissman, Michael B."]},{"key":"dc:creator","label":"Author","values":["Merithew, Robert David"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-05-29T18:31:44Z","10000-01-01","2000"]},{"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."]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["epitaxial single-crystal films"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["©2000 Merithew"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/31256","4340048"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Epitaxial single-crystal films of La2; 3Ca1; 3Mn03 exhibit large discrete equilibrium resistance fluctuations in the region of phase space where colossal magnetoresistance effects are strongest. The fluctuators' dependence on magnetic field indicates that the resistance steps represent small regions of material fluctuating between a paramagnetic insulating phase and a ferromagnetic conducting phase. The dependences of Boltzmann factors on field and temperature give the magnetic moment and entropy differences between the states, providing quantitative thermodynamic information about the locally homogeneous CMR phase transition in an otherwise inhomogeneous sample. The size of the discrete resistance fluctuations reveals a very inhomogeneous current density. The temperature dependence of some fluctuators provides evidence for thermodynamic effects which stabilize the mixed phase. A separate experiment on the spin glass CuMnAu investigates the effect of strong local anisotropy on spin glass dynamics. The result demonstrates that altering the symmetry of a spin glass Hamiltonian on the scale of the two-spin interaction has a strong qualitative effect on the low-energy frozen spin glass state space.","Submitted by William Weathers (weathrs2@illinois.edu) on 2012-05-29T18:31:44Z No. of bitstreams: 1 2000_merithew.pdf: 2491201 bytes, checksum: dbccb904622a83a3efdde4f6a743e01b (MD5)","Made available in DSpace on 2012-05-29T18:31:44Z (GMT). No. of bitstreams: 1 2000_merithew.pdf: 2491201 bytes, checksum: dbccb904622a83a3efdde4f6a743e01b (MD5) Previous issue date: 2000","Restriction data tranferred 2014-07-01T11:10:50-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by William Weathers (weathrs2@illinois.edu) on 2012-05-29T18:31:45Z Item is restricted indefinitely.","Thesis","U of I Only"]},{"key":"dc:title","label":"Title","values":["Mesoscopic noise probe of an inhomogeneous colossal magnetoresistance phase"]}]}],"canonical_facts":{"dc:contributor":["Weissman, Michael B."],"dc:creator":["Merithew, Robert David"],"dc:date":["2012-05-29T18:31:44Z","10000-01-01","2000"],"dc:description":["Epitaxial single-crystal films of La2; 3Ca1; 3Mn03 exhibit large discrete equilibrium resistance fluctuations in the region of phase space where colossal magnetoresistance effects are strongest. The fluctuators' dependence on magnetic field indicates that the resistance steps represent small regions of material fluctuating between a paramagnetic insulating phase and a ferromagnetic conducting phase. The dependences of Boltzmann factors on field and temperature give the magnetic moment and entropy differences between the states, providing quantitative thermodynamic information about the locally homogeneous CMR phase transition in an otherwise inhomogeneous sample. The size of the discrete resistance fluctuations reveals a very inhomogeneous current density. The temperature dependence of some fluctuators provides evidence for thermodynamic effects which stabilize the mixed phase. A separate experiment on the spin glass CuMnAu investigates the effect of strong local anisotropy on spin glass dynamics. The result demonstrates that altering the symmetry of a spin glass Hamiltonian on the scale of the two-spin interaction has a strong qualitative effect on the low-energy frozen spin glass state space.","Submitted by William Weathers (weathrs2@illinois.edu) on 2012-05-29T18:31:44Z No. of bitstreams: 1 2000_merithew.pdf: 2491201 bytes, checksum: dbccb904622a83a3efdde4f6a743e01b (MD5)","Made available in DSpace on 2012-05-29T18:31:44Z (GMT). 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