Competing Phases in Two-Dimensional Quantum Many-Body Systems

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dc.contributor.committeeMemberArmitage, N. Peteren_US
dc.contributor.committeeMemberKatz, Howard E.en_US
dc.contributor.committeeMemberMarkovic, Ninaen_US
dc.contributor.committeeMemberTchernyshyov, Oleg V.en_US
dc.contributor.committeeMemberYarkony, David R.en_US
dc.creatorMurray, James M.en_US
dc.date.accessioned2014-12-23T04:38:39Z
dc.date.available2014-12-23T04:38:39Z
dc.date.created2013-12en_US
dc.date.issued2013-10-22en_US
dc.date.submittedDecember 2013en_US
dc.description.abstractQuantum many-body systems exhibit a wide array of possible ordered phases at low temperatures. In this thesis, several such phases and the transitions between them are theoretically studied in the context of recent experimental results. I first present an investigation of fluctuation phenomena in layered superconductors in high magnetic fields. In order to account for the important effects of coupling between layers, which enhances the superconducting fluctuations and allows for a finite-temperature phase transition, a novel expansion in the number of coupled layers is used. This expansion leads to a two-dimensional effective Ginzburg--Landau theory, which allows for a controlled calculation of thermodynamic and transport properties such as magnetization and conductivity. Next, a microscopic mean-field analysis of the recently synthesized mixed-valency material KNi2Se2 is presented. Due to the noninteger number of localized electrons per unit cell and substantial degree of electron interactions, this material exhibits a tendency toward charge ordering, which competes with a heavy-fermion phase exhibiting an enhanced effective electron mass. Beginning from a microscopic Hamiltonian and applying mean-field theory, a reentrant charge-order transition is shown to exist theoretically, in apparent agreement with recent experimental observations. Finally, a renormalization group analysis is applied to the study of competing orders in bilayer graphene. In addition to the previously suggested nematic and antiferromagnetic phases, unconventional superconductivity is shown to arise generically in the presence of a nonzero chemical potential, even for the case where the bare interactions are entirely repulsive. The implications of these results on the general understanding of competition between particle-hole and superconducting orders are discussed in detail.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.urihttp://jhir.library.jhu.edu/handle/1774.2/37028
dc.languageen
dc.publisherJohns Hopkins University
dc.subjectquantum many-body physicsen_US
dc.subjectsuperconductivityen_US
dc.subjectheavy fermionsen_US
dc.subjectbilayer grapheneen_US
dc.titleCompeting Phases in Two-Dimensional Quantum Many-Body Systemsen_US
dc.typeThesisen_US
dc.type.materialtexten_US
local.embargo.lift2014-12-01en_US
local.embargo.terms2014-12-01en_US
thesis.degree.departmentPhysics and Astronomyen_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.grantorJohns Hopkins Universityen_US
thesis.degree.grantorKrieger School of Arts and Sciencesen_US
thesis.degree.levelDoctoralen_US
thesis.degree.namePh.D.en_US
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