Persistent Link:
http://hdl.handle.net/10150/195205
Title:
Magnetic Properties of Quasi-One-Dimensional Organic Conductors
Author:
Wu, Si
Issue Date:
2010
Publisher:
The University of Arizona.
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.
Abstract:
In the past three decades, quasi-low-dimensional organic materials have attracted intense interests, both experimentally and theoretically. Due to their reduced dimensionality and relatively low carrier concentration, many organic materials exhibit strong electron correlations and numerous instabilities of the normal metallic state. The energy scales of such instabilities are often so low that the ground states can be changed by applying a reasonably strong magnetic field. Therefore, magnetic field is an effective tool for the study of quasi-low-dimensional organic materials. In this thesis, we will investigate two of these magnetic field related phenomena. In the first part, we will present our unified theory of angular magnetoresistance oscillations observed in organic conductors. We will demonstrate that, in spite of the absence of Landau level quantization for open Fermi surfaces in a magnetic field, a new quantum effect - Bragg reflections of electrons moving in the extended Brillouin zone - determines unusual magnetic properties of these materials. We will demonstrate that, at commensurate directions of a magnetic field, the electron motion shows 1D→2D dimensional crossover and leads to strong resistivity minima. We will present an analytic expression for interlayer resistivity, by both linear response formalism and solving the Boltzmann kinetic equation in the extended Brillouin zone. In two limiting cases, our general solution reduces to the results previously obtained for the LMA effects and LNL oscillations. We demonstrate that our theoretical results are in good qualitative and quantitative agreement with the existing measurements of resistivity in (TMTSF)₂ClO₄ conductor. In the second part, we will develop a theory for the recently observed high magnetic field high resistance state in (Per)₂Pt(mnt)₂. We demonstrate that the Pauli spinsplitting effects in a magnetic field improve nesting properties of a realistic quasi-onedimensional electron spectrum. As a result, a high resistance Peierls charge-density wave (CDW) phase is stabilized in high enough magnetic fields in (Per)₂Pt(mnt)₂ conductor. We show that, in low and very high magnetic fields, the Pauli spin-splitting effects lead to a stabilization of a soliton wall superlattice (SWS) CDW phase, which is characterized by periodically arranged soliton and anti-soliton walls. We suggest experimental studies of the predicted first order phase transitions between the Peierls and SWS phases to discover a unique SWS phase. It is important that, in the absence of a magnetic field and in a limit of very high magnetic fields, the suggested model is equivalent to the exactly solvable model of Brazovskii, Dzyaloshinskii, and Kirova.
Type:
text; Electronic Dissertation
Keywords:
Condensed Matter Theory; Organic Conductors
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Physics; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Lebed, Andrei
Committee Chair:
Lebed, Andrei

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleMagnetic Properties of Quasi-One-Dimensional Organic Conductorsen_US
dc.creatorWu, Sien_US
dc.contributor.authorWu, Sien_US
dc.date.issued2010en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © 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.en_US
dc.description.abstractIn the past three decades, quasi-low-dimensional organic materials have attracted intense interests, both experimentally and theoretically. Due to their reduced dimensionality and relatively low carrier concentration, many organic materials exhibit strong electron correlations and numerous instabilities of the normal metallic state. The energy scales of such instabilities are often so low that the ground states can be changed by applying a reasonably strong magnetic field. Therefore, magnetic field is an effective tool for the study of quasi-low-dimensional organic materials. In this thesis, we will investigate two of these magnetic field related phenomena. In the first part, we will present our unified theory of angular magnetoresistance oscillations observed in organic conductors. We will demonstrate that, in spite of the absence of Landau level quantization for open Fermi surfaces in a magnetic field, a new quantum effect - Bragg reflections of electrons moving in the extended Brillouin zone - determines unusual magnetic properties of these materials. We will demonstrate that, at commensurate directions of a magnetic field, the electron motion shows 1D→2D dimensional crossover and leads to strong resistivity minima. We will present an analytic expression for interlayer resistivity, by both linear response formalism and solving the Boltzmann kinetic equation in the extended Brillouin zone. In two limiting cases, our general solution reduces to the results previously obtained for the LMA effects and LNL oscillations. We demonstrate that our theoretical results are in good qualitative and quantitative agreement with the existing measurements of resistivity in (TMTSF)₂ClO₄ conductor. In the second part, we will develop a theory for the recently observed high magnetic field high resistance state in (Per)₂Pt(mnt)₂. We demonstrate that the Pauli spinsplitting effects in a magnetic field improve nesting properties of a realistic quasi-onedimensional electron spectrum. As a result, a high resistance Peierls charge-density wave (CDW) phase is stabilized in high enough magnetic fields in (Per)₂Pt(mnt)₂ conductor. We show that, in low and very high magnetic fields, the Pauli spin-splitting effects lead to a stabilization of a soliton wall superlattice (SWS) CDW phase, which is characterized by periodically arranged soliton and anti-soliton walls. We suggest experimental studies of the predicted first order phase transitions between the Peierls and SWS phases to discover a unique SWS phase. It is important that, in the absence of a magnetic field and in a limit of very high magnetic fields, the suggested model is equivalent to the exactly solvable model of Brazovskii, Dzyaloshinskii, and Kirova.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectCondensed Matter Theoryen_US
dc.subjectOrganic Conductorsen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLebed, Andreien_US
dc.contributor.chairLebed, Andreien_US
dc.contributor.committeememberMazumdar, Sumiten_US
dc.contributor.committeememberStafford, Charlesen_US
dc.contributor.committeememberSu, Shufangen_US
dc.contributor.committeememberVisscher, Koenen_US
dc.identifier.proquest11226en_US
dc.identifier.oclc752261070en_US
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