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Characterization of topological insulators and semiconductors

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Title
Characterization of topological insulators and semiconductors
Name (type = personal)
NamePart (type = family)
Taherinejad
NamePart (type = given)
Maryam
NamePart (type = date)
1980-
DisplayForm
Maryam Taherinejad
Role
RoleTerm (authority = RULIB)
author
Name (type = personal)
NamePart (type = family)
Vanderbilt
NamePart (type = given)
David
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David Vanderbilt
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Advisory Committee
Role
RoleTerm (authority = RULIB)
chair
Name (type = personal)
NamePart (type = family)
Andrei
NamePart (type = given)
Eva
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Eva Andrei
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Advisory Committee
Role
RoleTerm (authority = RULIB)
internal member
Name (type = personal)
NamePart (type = family)
Haule
NamePart (type = given)
Kristjan
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Kristjan Haule
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Advisory Committee
Role
RoleTerm (authority = RULIB)
internal member
Name (type = personal)
NamePart (type = family)
Somerville
NamePart (type = given)
Rachel
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Rachel Somerville
Affiliation
Advisory Committee
Role
RoleTerm (authority = RULIB)
internal member
Name (type = personal)
NamePart (type = family)
Wu
NamePart (type = given)
Xifan
DisplayForm
Xifan Wu
Affiliation
Advisory Committee
Role
RoleTerm (authority = RULIB)
outside member
Name (type = corporate)
NamePart
Rutgers University
Role
RoleTerm (authority = RULIB)
degree grantor
Name (type = corporate)
NamePart
Graduate School - New Brunswick
Role
RoleTerm (authority = RULIB)
school
TypeOfResource
Text
Genre (authority = marcgt)
theses
OriginInfo
DateCreated (encoding = w3cdtf); (qualifier = exact)
2015
DateOther (qualifier = exact); (type = degree)
2015-10
CopyrightDate (encoding = w3cdtf); (qualifier = exact)
2015
Place
PlaceTerm (type = code)
xx
Language
LanguageTerm (authority = ISO639-2b); (type = code)
eng
Abstract (type = abstract)
The theoretical prediction and experimental observation of topological insulators (TIs) and semiconductors in recent years have opened the floodgates to many interesting physical phenomena and potential technological applications. A major part of this work is devoted to characterization of topological insulators and semiconductors. We argue that various kinds of TIs can be insightfully characterized by an inspection of the charge centers of the hybrid Wannier functions, defined as the orbitals obtained by carrying out a Wannier transform on the Bloch functions in one dimension while leaving them Bloch-like in the other two. From this procedure, one can obtain the Wannier charge centers (WCCs) and plot them in the two-dimensional projected Brillouin zone. We show that these WCC sheets contain the same kind of topological information as is carried in the surface energy bands, with the crucial advantage that the topological properties of the bulk can be deduced from bulk calculations alone. The distinct topological behaviors of these WCC sheets in trivial, Chern, weak, strong, crystalline TIs, and in Weyl semimetal, are first illustrated by calculating them for simple tight-binding models. We then present the results of first-principles calculations of the WCC sheets in the trivial insulator Sb$_2$Se$_3$, the weak TI KHgSb, and the strong TI Bi$_2$Se$_3$, confirming the ability of this approach to distinguish between different topological behaviors in an advantageous way. We also study the adiabatic pumping of the Chern-Simons axion (CSA) coupling along a parametric loop characterized by a non-zero second Chern number $C^{(2)}$ from the viewpoint of the hybrid Wannier representation. We derive a new formula for the CSA coupling, expressing it as an integral involving Berry curvatures and potentials defined on the WCC sheets. We show that a loop characterized by a non-zero $C^{(2)}$ requires a series of sheet-touching events at which $2pi$ quanta of Berry curvature are passed from sheet to sheet, in such a way that $e^2/h$ units of CSA coupling are pumped by a lattice vector by the end of the cycle. We illustrate these behaviors via explicit calculations on a model tight-binding Hamiltonian and discuss their implications. Finally, we study the Bloch-type domain walls in rhombohedral BaTiO$_3$. Ferroelectric domain walls (FDWs) are usually considered to be of Ising type, but there have been suggestions in recent years that Bloch-type FDWs are also possible in some cases, e.g., in the rhombohedral phase of BaTiO$_3$. The mechanically compatible and electrically neutral FDWs in rhombohedral BaTiO$_3$ are of 71$^circ$, 109$^circ$, and 180$^circ$ type. We have investigated these FDWs based both on first-principles calculations and on a Ginzburg-Landau-Devonshire (GLD) model. The results from both approaches confirm the Ising nature of the 71$^circ$ FDW and the Bloch nature of the 180$^circ$ FDW, and predict both Ising-type and Bloch-type FDWs are possible for the 109$^circ$ case. In view of the relatively small rhombohedral strain in BaTiO$_3$, the results can be explained reasonably well by regarding a Bloch FDW as composed of a pair of smaller-angle Ising FDWs, and by comparing the sum of the energies of these constituents with an Ising-type solution. A reduction by 40\% in the parameters describing the gradient term in the GLD model brings it into better agreement with the first-principles results for detailed properties such as the energies and widths of the FDWs.
Subject (authority = RUETD)
Topic
Physics and Astronomy
Subject (authority = ETD-LCSH)
Topic
Topological dynamics
Subject (authority = ETD-LCSH)
Topic
Semiconductors
RelatedItem (type = host)
TitleInfo
Title
Rutgers University Electronic Theses and Dissertations
Identifier (type = RULIB)
ETD
Identifier
ETD_6831
PhysicalDescription
Form (authority = gmd)
electronic resource
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application/pdf
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text/xml
Extent
1 online resource (xi, 92 p. : ill.)
Note (type = degree)
Ph.D.
Note (type = bibliography)
Includes bibliographical references
Note (type = statement of responsibility)
by Maryam Taherinejad
RelatedItem (type = host)
TitleInfo
Title
Graduate School - New Brunswick Electronic Theses and Dissertations
Identifier (type = local)
rucore19991600001
Location
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NjNbRU
Identifier (type = doi)
doi:10.7282/T3G73GQ6
Genre (authority = ExL-Esploro)
ETD doctoral
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The author owns the copyright to this work.
RightsHolder (type = personal)
Name
FamilyName
Taherinejad
GivenName
Maryam
Role
Copyright Holder
RightsEvent
Type
Permission or license
DateTime (encoding = w3cdtf); (qualifier = exact); (point = start)
2015-10-01 12:27:09
AssociatedEntity
Name
Maryam Taheri Nejad
Role
Copyright holder
Affiliation
Rutgers University. Graduate School - New Brunswick
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I hereby grant to the Rutgers University Libraries and to my school the non-exclusive right to archive, reproduce and distribute my thesis or dissertation, in whole or in part, and/or my abstract, in whole or in part, in and from an electronic format, subject to the release date subsequently stipulated in this submittal form and approved by my school. I represent and stipulate that the thesis or dissertation and its abstract are my original work, that they do not infringe or violate any rights of others, and that I make these grants as the sole owner of the rights to my thesis or dissertation and its abstract. I represent that I have obtained written permissions, when necessary, from the owner(s) of each third party copyrighted matter to be included in my thesis or dissertation and will supply copies of such upon request by my school. I acknowledge that RU ETD and my school will not distribute my thesis or dissertation or its abstract if, in their reasonable judgment, they believe all such rights have not been secured. I acknowledge that I retain ownership rights to the copyright of my work. I also retain the right to use all or part of this thesis or dissertation in future works, such as articles or books.
RightsEvent
DateTime (encoding = w3cdtf); (qualifier = exact); (point = start)
2015-10-31
DateTime (encoding = w3cdtf); (qualifier = exact); (point = end)
2017-10-30
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Embargo
Detail
Access to this PDF has been restricted at the author's request. It will be publicly available after October 30th, 2017.
Copyright
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Copyright protected
Availability
Status
Open
Reason
Permission or license
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ETD
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windows xp
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