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dc.contributor.advisorClay, R. Torsten
dc.contributor.authorHardikar, Rahul Padmakar
dc.date2007
dc.date.accessioned2020-05-07T18:24:54Z
dc.date.available2020-05-07T18:24:54Z
dc.identifier.urihttps://hdl.handle.net/11668/17263
dc.description.abstractWe study the unusual phases seen in charge transfer salts (CTS) at 1/2 and 1/4 filling. We use the Holstein-Hubbard model (HHM) and the Peierls extended Hubbard model (PEH) to study competing phases in CTS. In the 1/2-filled HHM the Holstein coupling promotes a Peierls charge-density wave phase while the on-site Coulomb repulsion U gives rise to antiferromagnetic correlations and a Mott insulating state. Takada et al. have shown possibility of a third metallic phase between the Mott and the Peierls phase. We investigate the presence of an intermediate phase between the Mott and Peierls phase using Stochastic Series Expansion (SSE) method. We used charge and spin susceptibilities to determine the phase boundaries. As the coupling is increased a spin gap opens followed by the Peierls transition. The intermediate phase is metallic and has a spin gap but no charge gap. Transitions from the Mott to intermediate and intermediate to Peierls state are Kosterlitz-Thouless type (KT). As the coulomb repulsion is increaed beyond certain value the two KT transitions fuse to give a single first order transition. Similar behavior is seen at 1/4-filled HHM. We also studied the temperature dependence of charge ordering (CO) in 1/4-filled CTS. Most previous theoretical studies of the on CTS have concentrated on ground state or T=0 properties. Here we show the evolution of charge ordered (CO) state with temperature and directly related the experimental phase diagram with our theoretical results. Our calculations show that as temperature is lowered the Wigner crystal state gives way to spin-Peierls state with a different pattern of CO. Also we show that the critical value of nearest neighbor Coulomb repulsion is depends on the total spin and is different for different spin subspace.
dc.publisherMississippi State University
dc.subject.lcshElectron-phonon interactions.
dc.subject.lcshHubbard model.
dc.subject.lcshEnergy-band theory of solids.
dc.subject.lcshOrganic superconductors.
dc.subject.othersuperconductivity
dc.subject.otherMott phase
dc.subject.otherPeierls phase
dc.subject.otherAutocorrelation time
dc.subject.otherCharge Ordering
dc.subject.otherPhase diagram
dc.subject.otherHolstein Hubbard model
dc.subject.otherTMTTF
dc.subject.otherorganic superconductors
dc.titleDynamic Electron-Phonon Interactions In One Dimensional Models
dc.typeDissertation
dc.publisher.departmentDepartment of Physics and Astronomy.
dc.publisher.collegeBagley College of Engineering
dc.date.authorbirth1978
dc.subject.degreeDoctor of Philosophy
dc.subject.majorPhysics and Astronomy
dc.contributor.committeeMonts, David L.
dc.contributor.committeeLuke, Edward
dc.contributor.committeeNovotny, Mark A.
dc.contributor.committeeGwaltney, Steven


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