{"id":{"repo_id":"arizona-thes","oai_identifier":"oai:repository.arizona.edu:10150/183928"},"canonical_url":"https://search.dev.ndltd.org/etd/arizona-thes/oai:repository.arizona.edu:10150/183928","repository":{"repo_id":"arizona-thes","name":"University of Arizona","base_url":"https://repository.arizona.edu/oai/request"},"display":{"title":"EXPERIMENTAL STUDIES OF QUANTUM OSCILLATIONS IN THE TRANSVERSE MAGNETORESISTANCE OF SINGLE-CRYSTALLINE, ULTRAPURE MAGNESIUM: NON-OHMIC EFFECTS.","abstract":"We report here the observation of non-ohmic behavior in the dominant oscillatory component (the cigar component) of ρ('H) in ultrapure magnesium when the magnetic field, 'H, is parallel to [0001] and the current density, 'J, lies in the basal plane. In order to study this new phenomenon systematically, we had to overcome two experimental problems. The first was the design of an experimental probe which could reproducibly control, at low temperatures, the contact resistance at one of the points where current is injected into the sample without disturbing the sample's orientation with respect to 'H. Special micromanipulators, controlled by helium gas pressure, were designed into the probe for this purpose. The second problem was the construction of a detector which had the sensitivity to measure small signals from the magnesium samples in an effort to investigate the low current regime where the oscillations appear to satisfy Ohm's Law. A superconducting chopper amplifier was built which had the sensitivity to measure 10⁻¹¹ volt signals. We present evidence which directly relates this non-ohmic behavior to the long-range influence of a relatively large contact resistance at a point where current is injected into the sample. Data are presented which indicate that when this non-ohmic behavior is present, the corresponding oscillation amplitudes are proportional to the contact resistance. Measurements are also presented which show that the effects of this local current injection are so nonlocal that they extend over distances which are comparable to the dimensions of the sample.","abstract_html":"We report here the observation of non-ohmic behavior in the dominant oscillatory component (the cigar component) of ρ('H) in ultrapure magnesium when the magnetic field, 'H, is parallel to [0001] and the current density, 'J, lies in the basal plane. In order to study this new phenomenon systematically, we had to overcome two experimental problems. The first was the design of an experimental probe which could reproducibly control, at low temperatures, the contact resistance at one of the points where current is injected into the sample without disturbing the sample's orientation with respect to 'H. Special micromanipulators, controlled by helium gas pressure, were designed into the probe for this purpose. The second problem was the construction of a detector which had the sensitivity to measure small signals from the magnesium samples in an effort to investigate the low current regime where the oscillations appear to satisfy Ohm's Law. A superconducting chopper amplifier was built which had the sensitivity to measure 10⁻¹¹ volt signals. We present evidence which directly relates this non-ohmic behavior to the long-range influence of a relatively large contact resistance at a point where current is injected into the sample. Data are presented which indicate that when this non-ohmic behavior is present, the corresponding oscillation amplitudes are proportional to the contact resistance. Measurements are also presented which show that the effects of this local current injection are so nonlocal that they extend over distances which are comparable to the dimensions of the sample.","abstract_has_math":false,"creators":["WHITTEMORE, THOMAS EDWARD."],"institution":"The University of Arizona.","degree_name":"Ph.D.","degree_level":"doctoral","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":[],"advisors":["Stark, W."],"committee_chairs":[],"committee_members":[],"year":1986,"date_issued":"1986","date_published":"1986","updated_at":"2026-07-24T00:56:34Z","subjects":["Magnesium.","Magnetic fields.","Ohm's law."],"languages":["en"],"rights":["Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10150/183928","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Stark, W."]},{"key":"dc:creator","label":"Author","values":["WHITTEMORE, THOMAS EDWARD."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2011-10-31T16:53:59Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2011-10-31T16:53:59Z"]},{"key":"dc:date.issued","label":"Date","values":["1986"]},{"key":"dc:publisher","label":"Institution","values":["The University of Arizona."]},{"key":"dc:type","label":"Dc Type","values":["text","Dissertation-Reproduction (electronic)"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics","Graduate College"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Arizona"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Magnesium.","Magnetic fields.","Ohm's law."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10150/183928"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["We report here the observation of non-ohmic behavior in the dominant oscillatory component (the cigar component) of ρ('H) in ultrapure magnesium when the magnetic field, 'H, is parallel to [0001] and the current density, 'J, lies in the basal plane. In order to study this new phenomenon systematically, we had to overcome two experimental problems. The first was the design of an experimental probe which could reproducibly control, at low temperatures, the contact resistance at one of the points where current is injected into the sample without disturbing the sample's orientation with respect to 'H. Special micromanipulators, controlled by helium gas pressure, were designed into the probe for this purpose. The second problem was the construction of a detector which had the sensitivity to measure small signals from the magnesium samples in an effort to investigate the low current regime where the oscillations appear to satisfy Ohm's Law. A superconducting chopper amplifier was built which had the sensitivity to measure 10⁻¹¹ volt signals. We present evidence which directly relates this non-ohmic behavior to the long-range influence of a relatively large contact resistance at a point where current is injected into the sample. Data are presented which indicate that when this non-ohmic behavior is present, the corresponding oscillation amplitudes are proportional to the contact resistance. Measurements are also presented which show that the effects of this local current injection are so nonlocal that they extend over distances which are comparable to the dimensions of the sample."]},{"key":"dc:title","label":"Title","values":["EXPERIMENTAL STUDIES OF QUANTUM OSCILLATIONS IN THE TRANSVERSE MAGNETORESISTANCE OF SINGLE-CRYSTALLINE, ULTRAPURE MAGNESIUM: NON-OHMIC EFFECTS."]}]}],"canonical_facts":{"dc:contributor.advisor":["Stark, W."],"dc:creator":["WHITTEMORE, THOMAS EDWARD."],"dc:date.accessioned":["2011-10-31T16:53:59Z"],"dc:date.available":["2011-10-31T16:53:59Z"],"dc:date.issued":["1986"],"dc:description.abstract":["We report here the observation of non-ohmic behavior in the dominant oscillatory component (the cigar component) of ρ('H) in ultrapure magnesium when the magnetic field, 'H, is parallel to [0001] and the current density, 'J, lies in the basal plane. In order to study this new phenomenon systematically, we had to overcome two experimental problems. The first was the design of an experimental probe which could reproducibly control, at low temperatures, the contact resistance at one of the points where current is injected into the sample without disturbing the sample's orientation with respect to 'H. Special micromanipulators, controlled by helium gas pressure, were designed into the probe for this purpose. The second problem was the construction of a detector which had the sensitivity to measure small signals from the magnesium samples in an effort to investigate the low current regime where the oscillations appear to satisfy Ohm's Law. A superconducting chopper amplifier was built which had the sensitivity to measure 10⁻¹¹ volt signals. We present evidence which directly relates this non-ohmic behavior to the long-range influence of a relatively large contact resistance at a point where current is injected into the sample. Data are presented which indicate that when this non-ohmic behavior is present, the corresponding oscillation amplitudes are proportional to the contact resistance. Measurements are also presented which show that the effects of this local current injection are so nonlocal that they extend over distances which are comparable to the dimensions of the sample."],"dc:identifier.uri":["http://hdl.handle.net/10150/183928"],"dc:language.iso":["en"],"dc:publisher":["The University of Arizona."],"dc:rights":["Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author."],"dc:subject":["Magnesium.","Magnetic fields.","Ohm's law."],"dc:title":["EXPERIMENTAL STUDIES OF QUANTUM OSCILLATIONS IN THE TRANSVERSE MAGNETORESISTANCE OF SINGLE-CRYSTALLINE, ULTRAPURE MAGNESIUM: NON-OHMIC EFFECTS."],"dc:type":["text","Dissertation-Reproduction (electronic)"],"thesis:degree_discipline":["Physics","Graduate College"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Arizona"]},"updated_at":"2026-07-24T00:56:34Z"}