On the Typical and Average Contributions to the Persistent Current in Mesoscopic Rings

dc.contributor.advisorWebb, Richard Aen_US
dc.contributor.authorJariwala, E. Manher Q.en_US
dc.contributor.departmentPhysicsen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2004-08-27T05:24:34Z
dc.date.available2004-08-27T05:24:34Z
dc.date.issued2004-07-27en_US
dc.description.abstractLow-temperature measurements of the magnetic response of one or more electrically-isolated, micron-sized metallic rings yield an unexpected yet unequivocal result: the presence of equilibrium <i>persistent</i> currents, with nanoampere-sized amplitudes and either <i>h/e</i>- or <i>h/2e</i>-periodicity in the applied magnetic flux. This effect follows from the extended phase coherence of the conduction electrons in this disordered mesoscopic system. As with transport phenomena, this thermodynamic effect demonstrates sample-specific as well as ensemble-averaging qualities common to mesoscopic physics. With few exceptions, however, there is strong disagreement between the different theoretical calculations and the few successful experiments to date. For this thesis work, we have designed and executed a unique and unprecedented new experiment: the measurement of the sign, amplitude, and temperature dependences of both the typical and average current contributions to the <i>h/e</i>- and <i>h/2e</i>-periodic magnetic response of the same sample of thirty mesoscopic Au rings. Of particular interest here is the innovative design of our custom SQUID-based detector as well as the unusually long phase coherence of electrons in our lithographically-patterned Au sample. Remarkably, both the typical and average contributions are diamagnetic in sign near zero field, over multiple cooldowns, and comparable in magnitude per ring to the Thouless scale E<sub>c</sub> of energy level correlations. Taken in conjunction with earlier experiments, the new data strongly challenge conventional theories of the persistent current.en_US
dc.format.extent1422249 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/1748
dc.language.isoen_US
dc.subject.pqcontrolledPhysics, Condensed Matteren_US
dc.subject.pquncontrolledpersistent currenten_US
dc.subject.pquncontrolledmesoscopicsen_US
dc.subject.pquncontrolledmesoscopic physicsen_US
dc.subject.pquncontrolleddecoherenceen_US
dc.subject.pquncontrollednanotechnologyen_US
dc.titleOn the Typical and Average Contributions to the Persistent Current in Mesoscopic Ringsen_US
dc.typeDissertationen_US

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