Open Access. Powered by Scholars. Published by Universities.®

Condensed Matter Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

1804 Full-Text Articles 2575 Authors 249838 Downloads 65 Institutions

All Articles in Condensed Matter Physics

Faceted Search

1804 full-text articles. Page 1 of 44.

Tuning Topological Surface States By Charge Transfer, Zhiyi Chen 2016 The Graduate Center, City University of New York

Tuning Topological Surface States By Charge Transfer, Zhiyi Chen

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

Three-dimensional (3D) topological insulators (TIs), Bi2Se3, Bi2Te3, Sb2Te3, are a class of materials that has non-trivial bulk band structure and metallic surface states. Access to charge transport through Dirac surface states in TIs can be challenging due to their intermixing with bulk states or non-topological two-dimensional electron gas quantum well states caused by bending of electronic bands near the surface. The band bending arises via charge transfer from surface adatoms or interfaces and, therefore, the choice of layers abutting topological surfaces is critical. Surfaces of these 3D TIs have also been ...


Alamethicin In Lipid Bilayers: Combined Use Of X-Ray Scattering And Md Simulations, Jianjun Pan, D. Peter Tieleman, John F. Nagle, Norbert Kučerka, Prof. Stephanie Tristram-Nagle Ph.D. 2016 Carnegie Mellon University

Alamethicin In Lipid Bilayers: Combined Use Of X-Ray Scattering And Md Simulations, Jianjun Pan, D. Peter Tieleman, John F. Nagle, Norbert Kučerka, Prof. Stephanie Tristram-Nagle Ph.D.

John Copeland Nagle

We study fully hydrated bilayers of two di-monounsaturated phospholipids diC18:1PC (DOPC) and diC22:1PC with varying amounts of alamethicin (Alm). We combine the use of X-ray diffuse scattering and molecular dynamics simulations to determine the orientation of alamethicin in model lipids. Comparison of the experimental and simulated form factors shows that Alm helices are inserted transmembrane at high humidity and high concentrations, in agreement with earlier results. The X-ray scattering data and the MD simulations agree that membrane thickness changes very little up to 1/10 Alm/ DOPC. In contrast, the X-ray data indicate that the thicker diC22:1PC ...


Self-Assembled Copper Nanoparticle Superlattices On Graphene Thin Films, Tianhao Ouyang 2016 The University of Western Ontario

Self-Assembled Copper Nanoparticle Superlattices On Graphene Thin Films, Tianhao Ouyang

Electronic Thesis and Dissertation Repository

Recently, Giovannetti et al. successfully demonstrated that some metals (such as Cu and Au) only have weak van der waals interaction with graphene and thus can only form weak bonding without severely shifting graphene’s band structure, which describes the energies range of the electrons in the material. Therefore, this opens up windows for graphene enhancement without greatly changing its properties. Furthermore, Zhou et al. later suggested the possibility of self-assembling periodic arrays of alkali atoms on graphene. In our group, graphene thin films fabricated in a cost effective way using solution-processed methods have been used extensively, including decorating graphene ...


Photonicstd-2d: Modeling Light Scattering In Periodic Multilayer Photonic Structures, Alexey Bondarev, Shaimaa Azzam, Zhaxylyk Kudyshev, Alexander V. Kildishev 2016 North Carolina State University at Raleigh

Photonicstd-2d: Modeling Light Scattering In Periodic Multilayer Photonic Structures, Alexey Bondarev, Shaimaa Azzam, Zhaxylyk Kudyshev, Alexander V. Kildishev

The Summer Undergraduate Research Fellowship (SURF) Symposium

Efficient modeling of electromagnetic processes in optical and plasmonic metamaterials is important for enabling new and exciting ways to manipulate light for advanced applications. In this work, we put together a tool for numerical simulation of propagation of normally incident light through a nanostructured multilayer composite material. The user builds a unit cell of a given material layer-by-layer starting from a substrate up to a superstrate, splitting each layer further into segments. The segments are defined by width and material -- dielectric, metal or active medium. Simulations are performed with the finite difference time domain (FDTD) method. A database of common ...


Classifying Pattern Formation In Materials Via Machine Learning, Lukasz Burzawa, Shuo Liu, Erica W. Carlson 2016 Purdue University

Classifying Pattern Formation In Materials Via Machine Learning, Lukasz Burzawa, Shuo Liu, Erica W. Carlson

The Summer Undergraduate Research Fellowship (SURF) Symposium

Scanning probe experiments such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM) on strongly correlated materials often reveal complex pattern formation that occurs on multiple length scales. We have shown in two disparate correlated materials that the pattern formation is driven by proximity to a disorder-driven critical point. We developed new analysis concepts and techniques that relate the observed pattern formation to critical exponents by analyzing the geometry and statistics of clusters observed in these experiments and converting that information into critical exponents. Machine learning algorithms can be helpful correlating data from scanning probe experiments to theoretical models ...


Low-Dimensional Materials For Organic Electronic Applications, Sumit Beniwal 2016 University of Nebraska-Lincoln

Low-Dimensional Materials For Organic Electronic Applications, Sumit Beniwal

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

This thesis explores the self-assembly, surface interactions and electronic properties of functional molecules that have potential applications in electronics. Three classes of molecules - organic ferroelectric, spin-crossover complex, and molecules that assemble into a 2D semiconductor, have been studied through scanning tunneling microscopy and surfacesensitive spectroscopic methods. The scientific goal of this thesis is to understand the self-assembly of these molecules in low-dimensional (2D) configurations and the influence of substrate on their properties. First, a H-bonded organic ferroelectric, the 3-Hydroxyphenalenone, is studied on two noble metal substrates. It is demonstrated how a variety of different assemblies including 1D chains, p-p stacked ...


Materials Design And Band Gap Engineering Of Complex Nanostructures Using A Semi-Empirical Approach : Low Dimensional Boron Nanostructures, H-Bn Sheet With Graphene Domains And Holey Graphene., Cherno Baba Kah 2016 University of Louisville

Materials Design And Band Gap Engineering Of Complex Nanostructures Using A Semi-Empirical Approach : Low Dimensional Boron Nanostructures, H-Bn Sheet With Graphene Domains And Holey Graphene., Cherno Baba Kah

Electronic Theses and Dissertations

This dissertation will explore the potential of a semi-empirical Hamiltonian, developed by the research group at the University of Louisville, in predicting the existence of new families of low-dimensional boron nanostructures based on icosahedral α-B12 clusters, and in tuning the band gaps of h-BN sheets with graphene domains and holey graphene. This semi-empirical Hamiltonian models electron-electron and electron-ion interactions using environment-dependent (ED) functions, and ion-ion interactions via usual pairwise terms. Additional features of our approach are that it uses a linear combination of atomic orbitals (LCAO) framework to describe the Hamiltonian and it calculates the charge distribution around a ...


Vibrational And Structural Signatures Of The Crossover Between Dense Glassy And Sparse Gel-Like Attractive Colloidal Packings, Matthew A. Lohr, Tim Still, Raman Ganti, Matthew D. Gratale, Zoey S. Davidson, Kevin B. Aptowicz, Carl P. Goodrich, Daniel M. Sussman, A. G. Yodh 2016 University of Pennsylvania

Vibrational And Structural Signatures Of The Crossover Between Dense Glassy And Sparse Gel-Like Attractive Colloidal Packings, Matthew A. Lohr, Tim Still, Raman Ganti, Matthew D. Gratale, Zoey S. Davidson, Kevin B. Aptowicz, Carl P. Goodrich, Daniel M. Sussman, A. G. Yodh

Kevin Aptowicz

We investigate the vibrational modes of quasi-two-dimensional disordered colloidal packings of hard colloidal spheres with short-range attractions as a function of packing fraction. Certain properties of the vibrational density of states (vDOS) are shown to correlate with the density and structure of the samples (i.e., in sparsely versus densely packed samples). Specifically, a crossover from dense glassy to sparse gel-like states is suggested by an excess of phonon modes at low frequency and by a variation in the slope of the vDOS with frequency at low frequency. This change in phonon mode distribution is demonstrated to arise largely from ...


Omcvd Gold Nanoparticles Covalently Attached To Polystyrene For Biosensing Applications, Sivayini Kandeepan 2016 The University of Western Ontario

Omcvd Gold Nanoparticles Covalently Attached To Polystyrene For Biosensing Applications, Sivayini Kandeepan

Electronic Thesis and Dissertation Repository

Remarkable developments and successes were witnessed in the fabrication and implementation of optical sensors based on localized surface plasmon resonance (LSPR) for the investigation of chemical and biological material quantities and to detect lethal diseases such as cancer in early stages. Gold nanoparticles (AuNPs) are ideal candidate for sensing purposes due to their chemical stability, ease of surface functionalization and strong LSPR in the visible range. Although there are several designs of sensors published, most of them are still limited to small scale research laboratory use partly due to their high cost of fabrication and waste management, in particular critical ...


Preparation And Characterization Of Van Der Waals Heterostructures, Horacio Coy Diaz 2016 University of South Florida

Preparation And Characterization Of Van Der Waals Heterostructures, Horacio Coy Diaz

Graduate Theses and Dissertations

In this dissertation different van der Waals heterostructures such as graphene-MoS2 and MoTe2-MoS2 were prepared and characterized. In the first heterostructure, polycrystalline graphene was synthesized by chemical vapor deposition and transferred on top of MoS2 single crystal. In the second heterostructure, MoTe2 monolayers were deposited on MoS2 by molecular beam epitaxy.

Characterization of graphene-MoS2 heterostructures was conducted by spin and angle resolve spectroscopy which showed that the electronic structure of the bulk MoS2 and graphene in this van der Waals heterostructures is modified. For MoS2 underneath the graphene, a band structure renormalization and spin polarization are observed. The band structure ...


Raman Scattering And Anomalous Stokes–Anti-Stokes Ratio In Mote2 Atomic Layers, Yan Jun 2016 University of Massachusetts Amherst

Raman Scattering And Anomalous Stokes–Anti-Stokes Ratio In Mote2 Atomic Layers, Yan Jun

Jun Yan

Stokes and anti-Stokes Raman scattering are performed on atomic layers of hexagonal molybdenum
ditelluride (MoTe2), a prototypical transition metal dichalcogenide (TMDC) semiconductor. The data
reveal all six types of zone center optical phonons, along with their corresponding Davydov splittings,
which have been challenging to see in other TMDCs. We discover that the anti-Stokes Raman intensity
of the low energy layer-breathing mode becomes more intense than the Stokes peak under certain
experimental conditions, and find the effect to be tunable by excitation frequency and number of
atomic layers. These observations are interpreted as a result of resonance effects arising from the ...


Classical Transport In Disordered Systems, Antonios Papaioannou 2016 Graduate Center, City University of New York

Classical Transport In Disordered Systems, Antonios Papaioannou

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

This thesis reports on the manifestation of structural disorder on molecular transport and it consists of two parts. Part I discusses the relations between classical transport and the underlying structural complexity of the system. Both types of molecular diffusion, namely Gaussian and non-Gaussian are presented and the relevant time regimes are discussed. In addition the concept of structural universality is introduced and connected with the diffusion metrics. One of the most robust techniques for measuring molecular mean square displacements is magnetic resonance. This method requires encoding and subsequently reading out after an experimentally controlled time, a phase ϕ to the ...


Modeling The Behavior Of The Graphene To Liquid Interfaces In An Electrolytic Liquid, Caitlin Duffner 2016 Linfield College

Modeling The Behavior Of The Graphene To Liquid Interfaces In An Electrolytic Liquid, Caitlin Duffner

Senior Theses

Understanding the mechanism for charge transfer between a graphene biosensor and its electrodes within an electrolyte solution is vital to better understand the sources of electrical noise in the system. By measuring the effective resistance and capacitance of the system at different frequencies, it is possible to develop a circuit model of the system's electrical behavior. This model provides a deeper understanding of the fundamental interactions that occur in a top-­gated graphene device and provides opportunities to improve a signal. To reduce noise created at the liquid to graphene interface, a buffer layer of Yttrium Oxide was applied ...


Effect Of Electrolyte Concentration On The Capacitance And Mobility Of Graphene, Flint A. Martino 2016 Linfield College

Effect Of Electrolyte Concentration On The Capacitance And Mobility Of Graphene, Flint A. Martino

Senior Theses

The use of graphene field-effect transistors as a biosensor is increasingly being used to study biological phenomena, due to the sensitivity and low reactivity of graphene. To further improve sensitivity in biological environments, we examined how different salt concentrations affect the mobility of capacitance of the graphene. Samples were also measured after an annealing process. We report on the positive correlation between sensitivity and electrolyte concentration and speculate on methods to improve future detectors. Mobility of the device was found to change from 1.07*103cm2/ (V*s) in de-ionized water to 2.78*103cm ...


Reflective Efficiencies Of Materials For Applications Of Bifacial Solar Cells, Michael Metter 2016 Linfield College

Reflective Efficiencies Of Materials For Applications Of Bifacial Solar Cells, Michael Metter

Senior Theses

The bifacial solar cell is superior to its monofacial predecessor due to its ability to convert both incident light on top and reflected light from below into energy. The scattering of the reflected light is affected by the property of the material on which it is interacting. To date, little work has been contributed to studying the properties of these materials to determine optimal quantities for bifacial solar cells. In the first experiment, reflective efficiencies compared to the angle of reflection were explored for different grit of sandpaper in order to develop an understanding of how surface texture impacts reflectivity ...


Searching To Distinguish Defects And The Presence Of Negative Capacitance, Thaddeus Cox 2016 Linfield College

Searching To Distinguish Defects And The Presence Of Negative Capacitance, Thaddeus Cox

Senior Theses

In the search for solar cells with lower manufacturing costs, thin film technology was developed. These thin films are only micrometers thick and are grown at relatively low temperatures, resulting in films with imperfections known as defects. Defects can cause thin film solar cells to have lower efficiencies than their single crystalline counterparts. In order to create more efficient thin film solar cells the physical mechanisms behind defects need to be investigated by sensitive techniques. Capacitance measurements of solar cells detect minute changes in charge in the material. For that reason, capacitance is used to electrically characterize the solar cell ...


Ferromagnetic Resonance Studies Of Coupled Magnetic Systems, Daniel J. Adams 2016 University of New Orleans

Ferromagnetic Resonance Studies Of Coupled Magnetic Systems, Daniel J. Adams

University of New Orleans Theses and Dissertations

The high-frequency properties of coupled magnetic systems have been investigated using vector network analyzer ferromagnetic resonance (VNA-FMR) spectroscopy. SAF structures consist of two ferromagnetic layers separated by a non-magnetic spacer, coupled through the indirect exchange interaction. The ferromagnetic layers of our samples were composed of FeCoB separated by a layer of Ru. The thickness of Ru was varied in the range of 8 to 18 Å among the samples studied. Antiferromagnetic coupling can be quickly identified by the major hysteresis loop (MHL).

A new way of displaying FMR data for these trilayer samples is presented which completely preserves the anisotropy ...


Giant Enhancement Of Magnetic Anisotropy In Ultrathin Manganite Films Via Nanoscale 1d Periodic Depth Modulation, A. Rajapitamahuni, L. Zhang, Mark A Koten, V. R. Singh, J. D. Burton, Evgeny Y. Tsymbal, Jeffrey E. Shield, Xia Hong 2016 University of Nebraska - Lincoln

Giant Enhancement Of Magnetic Anisotropy In Ultrathin Manganite Films Via Nanoscale 1d Periodic Depth Modulation, A. Rajapitamahuni, L. Zhang, Mark A Koten, V. R. Singh, J. D. Burton, Evgeny Y. Tsymbal, Jeffrey E. Shield, Xia Hong

Evgeny Tsymbal Publications

The relatively low magnetocrystalline anisotropy (MCA) in strongly correlated manganites (La,Sr)MnO3 has been a major hurdle for implementing them in spintronic applications. Here we report an unusual, giant enhancement of in-plane MCA in 6 nm La0.67Sr0.33MnO3 (LSMO) films grown on (001) SrTiO3 substrates when the top 2 nm is patterned into periodic stripes of 100 or 200 nm width. Planar Hall effect measurements reveal an emergent uniaxial anisotropy superimposed on one of the original biaxial easy axes for unpatterned LSMO along (110) directions, with a 50-fold enhanced anisotropy energy ...


Impedance Spectroscopy Studies Of Yttria Stabilized Zirconia Under Extreme Conditions, Quinlan Blaine Smith 2016 University of Nevada, Las Vegas

Impedance Spectroscopy Studies Of Yttria Stabilized Zirconia Under Extreme Conditions, Quinlan Blaine Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

Yttria Stabilized Zirconia (YSZ) is of interest for many industries. Varying amounts of Yttria (Y2O3) can be doped into Zirconia (ZrO2) to create materials with specific characteristics. For instance, 3mol% YSZ (3YSZ) is known to be a super hard material and is used as a coating on drill tips and as an abrasive. Eight mol% YSZ (8YSZ) is commonly used as a solid electrolyte in Solid Oxide Fuel Cells because of its good ionic conducting abilities and stability at high temperatures. In this thesis project, a novel experimental setup was created and used to study the ionic conductivity of (3 ...


High-Pressure Properties Of Several Narrow Bandgap Semiconductors From First-Principles Calculations, Andrew Michael Alvarado 2016 University of Nevada, Las Vegas

High-Pressure Properties Of Several Narrow Bandgap Semiconductors From First-Principles Calculations, Andrew Michael Alvarado

UNLV Theses, Dissertations, Professional Papers, and Capstones

The electronic, thermodynamic, and structural properties of three semiconducting materials, ZnO, InN, and PbS, at high pressure are investigated utilizing first-principles calculations based on density function theory. The first two systems, ZnO and InN, crystalize as hexagonal structures at ambient conditions and transition to a cubic structure at higher pressures. The last system, PbS, is cubic at ambient conditions, but transitions to an orthorhombic structure at higher pressure. At ambient conditions, these materials are well known semiconductors with vast amount of research and a variety of wide ranging applications in electrical devices. However, there is a lack of understanding of ...


Digital Commons powered by bepress