{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/98090"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/98090","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Phase transitions and vortex dynamics in superconducting island arrays","abstract":"In this thesis, we use superconducting island arrays as a platform for studying vortex motion and quantum phase transitions. We investigate superconducting vortex dynamics and lattice structures in superconducting arrays by performing electrical transport measurements on Nb island arrays on Au at milli-kelvin temperatures and finite fields. At low fillings, we observe anomalous vortex dynamics that we attribute to a history dependent dissipative force as the vortex moves through the lattice. At higher fillings, vortex-vortex interaction becomes significant and is dominated by collective vortex motion. We find that the transition from pinned to vortex lattice flow is split into two transitions as the filling is shifted from the commensurate filling regime, where the vortex lattice has strong crystalline order, to an incommensurate filling, where the vortex lattice no longer matches potential wells of the SNS array. We find that this behavior is consistent with domain wall motion in a polycrystalline vortex lattice at commensurate fillings. Superconducting island arrays can also be used to study phase transitions. Previous work in our group found that the onset of superconductivity in Nb islands was strongly dependent on the island spacing in the array. Performing follow up measurements, we find that the critical island temperature increases as the underlying Au is made thicker, indicating that this effect is dependent on the strength of electrical interactions between islands and is not due to normal metal suppression. Performing measurements on individual islands, we find that the vast majority of 260nm islands undergo a transition at temperatures far lower than those in island arrays, to the extent that they cannot be observed in a Helium 4 cryostat, and that there is a broad distribution of island critical temperatures observed. This suggests that the onset of superconductivity in rare ordered regions plays a significant role the onset of superconductivity in both the arrays samples and single islands. Lastly, we present work studying the superconductor to insulator transition in Sn island arrays on graphene as well as the technical difficulties involved.","abstract_html":"In this thesis, we use superconducting island arrays as a platform for studying vortex motion and quantum phase transitions. We investigate superconducting vortex dynamics and lattice structures in superconducting arrays by performing electrical transport measurements on Nb island arrays on Au at milli-kelvin temperatures and finite fields. At low fillings, we observe anomalous vortex dynamics that we attribute to a history dependent dissipative force as the vortex moves through the lattice. At higher fillings, vortex-vortex interaction becomes significant and is dominated by collective vortex motion. We find that the transition from pinned to vortex lattice flow is split into two transitions as the filling is shifted from the commensurate filling regime, where the vortex lattice has strong crystalline order, to an incommensurate filling, where the vortex lattice no longer matches potential wells of the SNS array. We find that this behavior is consistent with domain wall motion in a polycrystalline vortex lattice at commensurate fillings. Superconducting island arrays can also be used to study phase transitions. Previous work in our group found that the onset of superconductivity in Nb islands was strongly dependent on the island spacing in the array. Performing follow up measurements, we find that the critical island temperature increases as the underlying Au is made thicker, indicating that this effect is dependent on the strength of electrical interactions between islands and is not due to normal metal suppression. Performing measurements on individual islands, we find that the vast majority of 260nm islands undergo a transition at temperatures far lower than those in island arrays, to the extent that they cannot be observed in a Helium 4 cryostat, and that there is a broad distribution of island critical temperatures observed. This suggests that the onset of superconductivity in rare ordered regions plays a significant role the onset of superconductivity in both the arrays samples and single islands. Lastly, we present work studying the superconductor to insulator transition in Sn island arrays on graphene as well as the technical difficulties involved.","abstract_has_math":false,"creators":["Durkin, Malcolm Shaw"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Mason, Nadya","Bezryadin, Alexey","Hughes, Taylor L.","DeMarco, Brian"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2017,"date_issued":"2017-09-29T16:37:42Z","date_published":"2017-09-29T16:37:42Z","updated_at":"2026-07-22T22:24:34Z","subjects":["Superconductivity","Vortex","Condensed matter","Dynamics","Defect","Glass"],"languages":["en"],"rights":["Copyright 2017 Malcolm Durkin"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/98090","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Mason, Nadya","Bezryadin, Alexey","Hughes, Taylor L.","DeMarco, Brian"]},{"key":"dc:creator","label":"Author","values":["Durkin, Malcolm Shaw"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2017-09-29T16:37:42Z","2017-05-02","2017-08"]},{"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":["Superconductivity","Vortex","Condensed matter","Dynamics","Defect","Glass"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2017 Malcolm Durkin"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/98090"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["In this thesis, we use superconducting island arrays as a platform for studying vortex motion and quantum phase transitions. We investigate superconducting vortex dynamics and lattice structures in superconducting arrays by performing electrical transport measurements on Nb island arrays on Au at milli-kelvin temperatures and finite fields. At low fillings, we observe anomalous vortex dynamics that we attribute to a history dependent dissipative force as the vortex moves through the lattice. At higher fillings, vortex-vortex interaction becomes significant and is dominated by collective vortex motion. We find that the transition from pinned to vortex lattice flow is split into two transitions as the filling is shifted from the commensurate filling regime, where the vortex lattice has strong crystalline order, to an incommensurate filling, where the vortex lattice no longer matches potential wells of the SNS array. We find that this behavior is consistent with domain wall motion in a polycrystalline vortex lattice at commensurate fillings. Superconducting island arrays can also be used to study phase transitions. Previous work in our group found that the onset of superconductivity in Nb islands was strongly dependent on the island spacing in the array. Performing follow up measurements, we find that the critical island temperature increases as the underlying Au is made thicker, indicating that this effect is dependent on the strength of electrical interactions between islands and is not due to normal metal suppression. Performing measurements on individual islands, we find that the vast majority of 260nm islands undergo a transition at temperatures far lower than those in island arrays, to the extent that they cannot be observed in a Helium 4 cryostat, and that there is a broad distribution of island critical temperatures observed. This suggests that the onset of superconductivity in rare ordered regions plays a significant role the onset of superconductivity in both the arrays samples and single islands. Lastly, we present work studying the superconductor to insulator transition in Sn island arrays on graphene as well as the technical difficulties involved.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-09-29 without embargo terms","The student, Malcolm Durkin, accepted the attached license on 2017-04-24 at 13:55.","The student, Malcolm Durkin, submitted this Dissertation for approval on 2017-04-24 at 14:09.","This Dissertation was approved for publication on 2017-05-02 at 15:50.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11012 on 2017-09-29 at 11:25:34","Made available in DSpace on 2017-09-29T16:37:42Z (GMT). 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We investigate superconducting vortex dynamics and lattice structures in superconducting arrays by performing electrical transport measurements on Nb island arrays on Au at milli-kelvin temperatures and finite fields. At low fillings, we observe anomalous vortex dynamics that we attribute to a history dependent dissipative force as the vortex moves through the lattice. At higher fillings, vortex-vortex interaction becomes significant and is dominated by collective vortex motion. We find that the transition from pinned to vortex lattice flow is split into two transitions as the filling is shifted from the commensurate filling regime, where the vortex lattice has strong crystalline order, to an incommensurate filling, where the vortex lattice no longer matches potential wells of the SNS array. We find that this behavior is consistent with domain wall motion in a polycrystalline vortex lattice at commensurate fillings. Superconducting island arrays can also be used to study phase transitions. Previous work in our group found that the onset of superconductivity in Nb islands was strongly dependent on the island spacing in the array. Performing follow up measurements, we find that the critical island temperature increases as the underlying Au is made thicker, indicating that this effect is dependent on the strength of electrical interactions between islands and is not due to normal metal suppression. Performing measurements on individual islands, we find that the vast majority of 260nm islands undergo a transition at temperatures far lower than those in island arrays, to the extent that they cannot be observed in a Helium 4 cryostat, and that there is a broad distribution of island critical temperatures observed. This suggests that the onset of superconductivity in rare ordered regions plays a significant role the onset of superconductivity in both the arrays samples and single islands. Lastly, we present work studying the superconductor to insulator transition in Sn island arrays on graphene as well as the technical difficulties involved.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-09-29 without embargo terms","The student, Malcolm Durkin, accepted the attached license on 2017-04-24 at 13:55.","The student, Malcolm Durkin, submitted this Dissertation for approval on 2017-04-24 at 14:09.","This Dissertation was approved for publication on 2017-05-02 at 15:50.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11012 on 2017-09-29 at 11:25:34","Made available in DSpace on 2017-09-29T16:37:42Z (GMT). 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