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2009

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Full-Text Articles in Physics

Integration Of Electronic And Optical Techniques In The Design And Fabrication Of Pressure Sensors, Ivan Padron Dec 2009

Integration Of Electronic And Optical Techniques In The Design And Fabrication Of Pressure Sensors, Ivan Padron

Dissertations

Since the introduction of micro-electro-mechanical systems fabrication methods, piezoresistive pressure sensors have become the more popular pressure transducers. They dominate pressure sensor commercialization due to their high performance, stability and repeatability. However, increasing demand for harsh environment sensing devices has made sensors based on Fabry-Perot interferometry the more promising optical pressure sensors due to their high degree of sensitivity, small size, high temperature performance, versatility, and improved immunity to environmental noise and interference. The work presented in this dissertation comprises the design, fabrication, and testing of sensors that fuse these two pressure sensing technologies into one integrated unit. A key ...


Relationship Between Photospheric Magnetic Fields And Coronal Activities, Changyi Tan Dec 2009

Relationship Between Photospheric Magnetic Fields And Coronal Activities, Changyi Tan

Dissertations

Coronal emission comes in two forms, a steady component where the corona is heated to million degrees and a much hotter transient component of solar flares. Both components are known to be related to the evolution of surface magnetic fields. This dissertation studies the evolution of photospheric magnetic fields and flow fields and their relation to the properties of these two coronal emission components.

The key issue in the study of the steady coronal emission is the coronal heating problem: how the corona is heated to millions of degrees while the underlying solar photosphere is only a few thousand degrees ...


Partial Wave Analysis Of The Reaction Γp And The Search For Nucleon Resonances, M. Williams, Gerard P. Gilfoyle, Et. Al. Dec 2009

Partial Wave Analysis Of The Reaction Γp→Pω And The Search For Nucleon Resonances, M. Williams, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

An event-based partial wave analysis (PWA) of the reaction γp has been performed on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world’s first high-precision spin-density matrix element measurements, available to the event-based PWA through the decay distribution of ωπ +π π0. The data confirm the dominance of the t-channel π0 exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F15(1680) and D13(1700 ...


Differential Cross Sections And Spin Density Matrix Elements For The Reaction Γp, M. Williams, Gerard P. Gilfoyle, Et. Al. Dec 2009

Differential Cross Sections And Spin Density Matrix Elements For The Reaction Γp→Pω, M. Williams, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

High-statistics differential cross sections and spin-density matrix elements for the reaction γp have been measured using the CEBAF large acceptance spectrometer (CLAS) at Jefferson Lab for center-of-mass (c.m.) energies from threshold up to 2.84 GeV. Results are reported in 112 10-MeV wide c.m. energy bins, each subdivided into cos θωc.m. bins of width 0.1. These are the most precise and extensive ω photoproduction measurements to date. A number of prominent structures are clearly present in the data. Many of these have not previously been observed due to limited statistics in earlier measurements.


Equalization Of Loudspeakers And Enclosed Sound Fields, Xi Chen Dec 2009

Equalization Of Loudspeakers And Enclosed Sound Fields, Xi Chen

Theses and Dissertations

Equalization of loudspeakers and enclosed sound fields has been a topic of considerable interest for decades. Confusion has often arisen among audio professionals regarding the feasibility of simultaneously equalizing a loudspeaker and the enclosed field (i.e., the “room”) it excites. Because of frustrations encountered in such efforts, some have advocated abandoning simultaneous equalization altogether. This dissertation discusses the drawbacks of this approach as well as traditional in situ equalization methods. It demonstrates that many problems with traditional equalization stem from the use of measured acoustic pressure at a discrete point in a sound field as the system output. The ...


A High-Yield Synthesis Of Chalcopyrite Cuins2 Nanoparticles With Exceptional Size Control, Aaron Thurber, Alex Punnoose Dec 2009

A High-Yield Synthesis Of Chalcopyrite Cuins2 Nanoparticles With Exceptional Size Control, Aaron Thurber, Alex Punnoose

Physics Faculty Publications and Presentations

We report high-yield and efficient size-controlled syntheses of Chalcopyrite CuInS2 nanoparticles by decomposing molecular single source precursors (SSPs) via microwave irradiation in the presence of 1,2-ethanedithiol at reaction temperatures as low as 100◦C and times as short as 30 minutes. The nanoparticles sizes were 1.8nm to 10.8 nm as reaction temperatures were varied from 100◦C to 200◦C with the bandgaps from 2.71 eV to 1.28 eV with good size control and high yields (64%–95%). The resulting nanoparticles were analyzed by XRD, UV-Vis, ICP-OES, XPS, SEM, EDS, and HRTEM. Titration studies ...


Optical Control Of Thermocapillary Effects In Complex Nanofluids, Yuval Lamhot, Assaf Barak, Carmel Rotschild, Mordechai Segev, Meirav Saraf, Efrat Lifshitz, Abraham Marmur, Ramy El-Ganainy, Demetrios N. Christodoulides Dec 2009

Optical Control Of Thermocapillary Effects In Complex Nanofluids, Yuval Lamhot, Assaf Barak, Carmel Rotschild, Mordechai Segev, Meirav Saraf, Efrat Lifshitz, Abraham Marmur, Ramy El-Ganainy, Demetrios N. Christodoulides

Ramy El-Ganainy

We study the strong coupling of light and nanoparticle suspensions and their surface tension effect in capillaries. We show experimentally and theoretically that increasing the intensity of a narrow laser beam passing through a capillary far away from the surface results in a significant decrease in the fluid level. The underlying mechanism relies on light-induced redistribution of nanoparticles in the bulk and the surface of the fluid, facilitating continuous optical control over the surface position. The experiments manifest optical control from afar over properties of fluid surfaces.


Structural Studies Of Large Integral Membrane Proteins In Reverse Micelles By Solution Nuclear Magnetic Resonance, Joseph Kielec Dec 2009

Structural Studies Of Large Integral Membrane Proteins In Reverse Micelles By Solution Nuclear Magnetic Resonance, Joseph Kielec

Publicly Accessible Penn Dissertations

The structural characterization of integral membrane proteins represents one of the many challenges of the post-genomic era. While membrane proteins comprise approximately 50% of current and potential drug targets, their structural characterization lags far behind that of soluble proteins. Nuclear magnetic resonance (NMR) offers tremendous potential for the investigation of membrane proteins in aqueous environments with respect to structural characterization, relaxation properties, and the details of small ligand interactions. However, the size limitations of solution NMR due to the slow tumbling problem have restricted comprehensive structural characterization of membrane protein NMR structures to the relatively small β-barrel proteins or helical ...


Casimir Interactions Between Scatterers In Carbon Nanotubes, Dina Zhabinskaya Dec 2009

Casimir Interactions Between Scatterers In Carbon Nanotubes, Dina Zhabinskaya

Publicly Accessible Penn Dissertations

In this thesis we calculate interactions between localized scatterers in metallic carbon nanotubes. Backscattering of electrons between localized scatterers mediates long range forces between them. These interactions are mapped to Casimir forces mediated by one-dimensional massless fermions and calculated using a force operator approach. We first study interactions between scatterers described by spinor polarized potentials relevant to the single-valley problem in carbon nanotubes. We obtain the force between two finite width square barriers, and take the limit of zero width and infinite potential strength to study the Casimir force mediated by the fermions. For the case of identical scatterers we ...


Galaxy-Cmb And Galaxy-Galaxy Lensing On Large Scales: Sensitivity To Primordial Non-Gaussianity, Donghui Jeong, Eiichiro Komatsu, Bhuvnesh Jain Dec 2009

Galaxy-Cmb And Galaxy-Galaxy Lensing On Large Scales: Sensitivity To Primordial Non-Gaussianity, Donghui Jeong, Eiichiro Komatsu, Bhuvnesh Jain

Department of Physics Papers

A convincing detection of primordial non-Gaussianity in the local form of the bispectrum, whose amplitude is given by the ƒNL parameter, offers a powerful test of inflation. In this paper, we calculate the modification of two-point cross-correlation statistics of weak lensing—galaxy-galaxy lensing and galaxycosmic microwave background (CMB) crosscorrelation—due to ƒNL. We derive and calculate the covariance matrix of galaxy-galaxy lensing, including cosmic variance terms. We focus on large scales (l < 100) for which the shape noise of the shear measurement becomes irrelevant and cosmic variance dominates the error budget. For a modest degree of non-Gaussianity, ƒNL = ±50 modifications of the galaxy-galaxy-lensing signal at the 10% level are seen on scales R ~ 300 Mpc, and grow rapidly toward larger scales as ∝ R ...


Electrically Reconfigurable Optical Metamaterial Based On Colloidal Dispersion Of Metal Nanorods In Dielectric Fluid, Andrii B. Golovin, Oleg Lavrentovich Dec 2009

Electrically Reconfigurable Optical Metamaterial Based On Colloidal Dispersion Of Metal Nanorods In Dielectric Fluid, Andrii B. Golovin, Oleg Lavrentovich

Chemical Physics Publications

Optical metamaterials capture the imagination with breathtaking promises of nanoscale resolution in imaging and invisibility cloaking. We demonstrate an approach to construct a metamaterial in which metallic nanorods, of dimension much smaller than the wavelength of light, are suspended in a fluid and placed in a nonuniform electric field. The field controls the spatial distribution and orientation of nanorods because of the dielectrophoretic effect. The field-controlled placement of nanorods causes optical effects such as varying refractive index, optical anisotropy (birefringence), and reduced visibility of an object enclosed by the metamaterial.


Helical Nanofilaments And The High Chiralty Limit Of Smectics A, Elisabetta A. Matsumoto, Gareth P. Alexander, Randal D. Kamien Dec 2009

Helical Nanofilaments And The High Chiralty Limit Of Smectics A, Elisabetta A. Matsumoto, Gareth P. Alexander, Randal D. Kamien

Department of Physics Papers

Liquid crystalline systems exhibiting both macroscopic chirality and smectic order experience frustration resulting in mesophases possessing complex three-dimensional order. In the twist-grainboundary phase, defect lattices mediate the propagation of twist throughout the system. We propose a new chiral smectic structure composed of a lattice of chiral bundles as a model of the helical nanofilament (B4) phase of bent-core smectics.


Carbon Coated Tellurium For Optical Data Storage, Jonathan D. Abbott Dec 2009

Carbon Coated Tellurium For Optical Data Storage, Jonathan D. Abbott

Theses and Dissertations

A highly durable optical disk has been developed for data archiving. This optical disk uses tellurium as the write layer and carbon as a dielectric and oxidation prevention layer. The sandwich style CTeC film was deposited on polycarbonate and silicon substrates by plasma sputtering. These films were then characterized with SEM, TEM, EELS, ellipsometry, ToF-SIMS, etc, and were tested for writability and longevity. Results show the films were uniform in physical structure, are stable, and able to form permanent pits. Data was written to a disk and successfully read back in a commercial DVD drive.


Reevaluating The Cosmological Origin Of Dark Matter, Scott Watson Dec 2009

Reevaluating The Cosmological Origin Of Dark Matter, Scott Watson

Physics

The origin of dark matter as a thermal relic offers a compelling way in which the early universe was initially populated by dark matter. Alternative explanations typically appear exotic compared to the simplicity of thermal production. However, recent observations and progress from theory suggest that it may be necessary to be more critical. This is important because ongoing searches probing the microscopic properties of dark matter typically rely on the assumption of dark matter as a single, unique, thermal relic. On general grounds I will argue that non-thermal production of dark matter seems to be a robust prediction of physics ...


Berry-Like Phases In Structured Atoms And Molecules, Edmund R. Meyer, Aaron E. Leanhardt, Eric A. Cornell, John L. Bohn Dec 2009

Berry-Like Phases In Structured Atoms And Molecules, Edmund R. Meyer, Aaron E. Leanhardt, Eric A. Cornell, John L. Bohn

Physics Faculty Contributions

Quantum mechanical phases arising from a periodically varying Hamiltonian are considered. These phases are derived from the eigenvalues of a stationary, “dressed” Hamiltonian that is able to treat internal atomic or molecular structure in addition to the time variation. In the limit of an adiabatic time variation, the usual Berry phase is recovered. For more rapid variation, nonadiabatic corrections to the Berry phase are recovered in perturbation theory, and their explicit dependence on internal structure emerges. Simple demonstrations of this formalism are given, to particles containing interacting spins, and to molecules in electric fields.


Measured Optical Constants Of Copper From 10 Nm To 35 Nm, David D. Allred, Nicole Brimhall, Nicholas Herrick, Justin Peatross, R. Steven Turley, Michael Ware Dec 2009

Measured Optical Constants Of Copper From 10 Nm To 35 Nm, David D. Allred, Nicole Brimhall, Nicholas Herrick, Justin Peatross, R. Steven Turley, Michael Ware

Faculty Publications

We use laser high-order harmonics and a polarization-ratioreflectance technique to determine the optical constants of copper and oxidized copper in the wavelength range 10-35 nm. This measurement resolves previously conflicting data sets, where disagreement on optical constants of copper in the extreme ultraviolet most likely arises from inadvertent oxidation of samples before measurement.


Non-Gaussian Signatures From The Postinflationary Early Universe, Alessandra Silvestri, Mark Trodden Dec 2009

Non-Gaussian Signatures From The Postinflationary Early Universe, Alessandra Silvestri, Mark Trodden

Department of Physics Papers

We consider contributions to non-Gaussianity of the cosmic microwave background (CMB) from remnants of phase transitions in the very early Universe. Such signatures can optimistically be used to discover evidence of new particle physics through cosmological observations. More conservatively they may provide an obstacle to extracting information about the non-Gaussian nature of primordial density fluctuations from any detection in the CMB. We study this explicitly by computing the bispectrum from global textures, which occur in a wide class of particle physics models.


Fractal Location And Anomalous Diffusion Dynamics For Oil Wells From The Ky Geological Survey, Keith Andrew, Karla M. Andrew, Kevin A. Andrew Dec 2009

Fractal Location And Anomalous Diffusion Dynamics For Oil Wells From The Ky Geological Survey, Keith Andrew, Karla M. Andrew, Kevin A. Andrew

Physics & Astronomy Faculty Publications

Utilizing data available from the Kentucky Geonet (KYGeonet.ky.gov) the fossil fuel mining locations created by the Kentucky Geological Survey geo-locating oil and gas wells are mapped using ESRI ArcGIS in Kentucky single plain 1602 ft projection. This data was then exported into a spreadsheet showing latitude and longitude for each point to be used for modeling at different scales to determine the fractal dimension of the set. Following the porosity and diffusivity studies of Tarafdar and Roy[1] we extract fractal dimensions of the fossil fuel mining locations and search for evidence of scaling laws for the set ...


Can Cosmic Parallax Distinguish Between Anisotrophic Cosmologies?, Michele Fontanini, Eric J. West, Mark Trodden Dec 2009

Can Cosmic Parallax Distinguish Between Anisotrophic Cosmologies?, Michele Fontanini, Eric J. West, Mark Trodden

Department of Physics Papers

In an anisotropic universe, observers not positioned at a point of special symmetry should observe cosmic parallax—the relative angular motion of test galaxies over cosmic time. It was recently argued that the nonobservance of this effect in upcoming precision astrometry missions such as GAIA may be used to place strong bounds on the position of off-center observers in a void-model universe described by the Lemaitre-Tolman-Bondi metric. We consider the analogous effect in anisotropic cosmological models described by an axisymmetric homogeneous Bianchi type I metric and discuss whether any observation of cosmic parallax would distinguish between different anisotropic evolutions.


Equivalence Of Glass Transition And Colloidal Glass Transition In The Hard-Sphere Limit, Ning Xu, Thomas K. Haxton, Andrea J. Liu, Sidney R. Nagel Dec 2009

Equivalence Of Glass Transition And Colloidal Glass Transition In The Hard-Sphere Limit, Ning Xu, Thomas K. Haxton, Andrea J. Liu, Sidney R. Nagel

Department of Physics Papers

We show that the slowing of the dynamics in simulations of several model glass-forming liquids is equivalent to the hard-sphere glass transition in the low-pressure limit. In this limit, we find universal behavior of the relaxation time by collapsing molecular-dynamics data for all systems studied onto a single curve as a function of T/p, the ratio of the temperature to the pressure. At higher pressures, there are deviations from this universal behavior that depend on the interparticle potential, implying that additional physical processes must enter into the dynamics of glass formation.


Midwave Infrared Imaging Fourier Transform Spectrometry Of Combustion Plumes, Kenneth C. Bradley Dec 2009

Midwave Infrared Imaging Fourier Transform Spectrometry Of Combustion Plumes, Kenneth C. Bradley

Theses and Dissertations

A midwave infrared (MWIR) imaging Fourier transform spectrometer (IFTS) was used to successfully capture and analyze hyperspectral imagery of combustion plumes. Jet engine exhaust data from a small turbojet engine burning diesel fuel at a flow rate of 300 cm3/min was collected at 1 cm−1 resolution from a side-plume vantage point on a 200x64 pixel window at a range of 11.2 meters. Spectral features of water, CO, and CO2 were present, and showed spatial variability within the plume structure. An array of thermocouple probes was positioned within the plume to aid in temperature analysis. A ...


Analysis Of Expedient Field Decontamination Methods For The Xmx/2l-Mil High-Volume Aerosol Sampler, Brandon C. Laroche Dec 2009

Analysis Of Expedient Field Decontamination Methods For The Xmx/2l-Mil High-Volume Aerosol Sampler, Brandon C. Laroche

Theses and Dissertations

The XMX/2L-MIL is a high volume air sampler used by the Air Force Bioenvironmental Engineering community to collect biological aerosols. Without a verified decontamination technique, however, the XMX cannot be used effectively. The objective of this study was to evaluate several proposed methods for expedient field decontamination of the XMX. This study centered on the inactivation of Bacillus atrophaeus spores and vegetative Erwinia herbicola organisms from the XMX inner canister. The goals in this investigation were twofold: 1) to verify the antimicrobial efficacy of a 10% bleach solution and 2) to determine if wiping the components with a bleach-soaked ...


Viscosity Dependent Liquid Slip At Molecularly Smooth Hydrophobic Surfaces, Sean P. Mcbride, Bruce M. Law Dec 2009

Viscosity Dependent Liquid Slip At Molecularly Smooth Hydrophobic Surfaces, Sean P. Mcbride, Bruce M. Law

Physics Faculty Research

Colloidal probe atomic force microscopy is used to study the slip behavior of 18 Newtonian liquids from two homologous series, the n-alkanes and n-alcohols, at molecularly smooth hydrophobic n-hexadecyltrichlorosilane coated surfaces. We find that the slip behavior is governed by the bulk viscosity η of the liquid, specifically, the slip length b∼ηx with x∼0.33. Additionally, the slip length was found to be shear rate independent, validating the use of Vinogradova slip theory in this work.


Are Black Holes Really Two Dimensional?, Vijay Balasubramanian Dec 2009

Are Black Holes Really Two Dimensional?, Vijay Balasubramanian

Department of Physics Papers

No abstract provided.


Large Flow Birefringence Of Nematogenic Bent-Core Liquid Crystals, C. Bailey, Katalin Fodor-Csorba, Rafael Verduzco, Jim T. Gleeson, Samuel N. Sprunt, Antal Jakli Dec 2009

Large Flow Birefringence Of Nematogenic Bent-Core Liquid Crystals, C. Bailey, Katalin Fodor-Csorba, Rafael Verduzco, Jim T. Gleeson, Samuel N. Sprunt, Antal Jakli

Chemical Physics Publications

We have found that bent-core liquid crystalline materials show exceptionally large intrinsic flow birefringence in their isotropic liquid phase. This effect is more than 100 times larger than typical values measured for low molecular weight liquid crystals. The specific flow birefringence (i.e., normalized by the flow viscosity) is an order of magnitude larger than in both side-chain polymeric as well as low molecular weight liquid crystals. We propose that this large enhancement for bent-core compounds may be attributed to nanoscale smecticlike clusters that persist above the nematic-isotropic transition temperature, and shear align under shear flow; however, this mechanism has ...


Flux Growth At Ambient Pressure Of Millimeter-Sized Single Crystals Of Lafeaso, Lafeaso1−Xfx, And Lafe1−Xcoxaso, J.-Q. Yan, Shibabrata Nandi, Jerel L. Zarestky, W. Tian, Andreas Kreyssig, Brandt A. Jensen, A. Kracher, Kevin W. Dennis, Robert J. Mcqueeney, Alan I. Goldman, R. William Mccallum, Thomas A. Lograsso Dec 2009

Flux Growth At Ambient Pressure Of Millimeter-Sized Single Crystals Of Lafeaso, Lafeaso1−Xfx, And Lafe1−Xcoxaso, J.-Q. Yan, Shibabrata Nandi, Jerel L. Zarestky, W. Tian, Andreas Kreyssig, Brandt A. Jensen, A. Kracher, Kevin W. Dennis, Robert J. Mcqueeney, Alan I. Goldman, R. William Mccallum, Thomas A. Lograsso

Ames Laboratory Publications

Millimeter-sized single crystals of LaFeAsO, LaFeAsO1−xFx, and LaFe1−xCoxAsO were grown in NaAs flux at ambient pressure. The detailed growth procedure and crystal characterizations are reported. The as-grown crystals have typical dimensions of3×4×0.05–0.3 mm3 with the crystallographic c-axis perpendicular to the plane of the platelike single crystals. Various characterizations confirmed the high quality of our LaFeAsO crystals. Co and F were introduced into the lattice leading to superconductingLaFe1−xCoxAsO and LaFeAsO1−xFx single crystals, respectively. This growth protocol ...


Nanoscopic Investigation Of Surface Morphology Of Neural Growth Cones And Indium Containing Group-Iii Nitrides, Göksel Durkaya Dec 2009

Nanoscopic Investigation Of Surface Morphology Of Neural Growth Cones And Indium Containing Group-Iii Nitrides, Göksel Durkaya

Physics and Astronomy Dissertations

This research focuses on the nanoscopic investigation of the three-dimensional surface morphology of the neural growth cones from the snail Helisoma trivolvis, and InN and InGaN semiconductor material systems using Atomic Force Microscopy (AFM). In the analysis of the growth cones, the results obtained from AFM experiments have been used to construct a 3D architecture model for filopodia. The filopodia from B5 and B19 neurons have exhibited different tapering mechanisms. The volumetric analysis has been used to estimate free Ca2+ concentration in the filopodium. The Phase Contrast Microscopy (PCM) images of the growth cones have been corrected to thickness provided ...


Analysis Of Gan/Alxga1−Xn Heterojunction Dual-Band Photodetectors Using Capacitance Profiling Techniques, Laura E. Byrum Dec 2009

Analysis Of Gan/Alxga1−Xn Heterojunction Dual-Band Photodetectors Using Capacitance Profiling Techniques, Laura E. Byrum

Physics and Astronomy Theses

Capacitance-voltage-frequency measurements on n+-GaN/AlxGa1−xN UV/IR dual-band detectors are reported. The presence of shallow Si-donor, deep Si-donor, and C-donor/N-vacancy defect states were found to significantly alter the electrical characteristics of the detectors. The barrier Al fraction was found to change the position of the interface defect states relative to the Fermi level. The sample with Al fraction of 0.1 shows a distinct capacitance-step and hysteresis, which is attributed to C-donor/N-vacancy electron trap states located above the Fermi level (200 meV) at the heterointerface; whereas, the sample with Al fraction of 0.026 shows negative ...


Self-Organized Criticality In Sheared Suspensions, L. Corté, Sharon J. Gerbode, W. Man, D. J. Pine Dec 2009

Self-Organized Criticality In Sheared Suspensions, L. Corté, Sharon J. Gerbode, W. Man, D. J. Pine

All HMC Faculty Publications and Research

Recent studies reveal that suspensions of neutrally buoyant non-Brownian particles driven by slow periodic shear can undergo a dynamical phase transition between a fluctuating irreversible steady state and an absorbing reversible state. Using a computer model, we show that such systems exhibit self-organized criticality when a finite particle sedimentation velocity vs is introduced. Under periodic shear, these systems evolve, without external intervention, towards the shear-dependent critical concentration ϕc as vs is reduced. This state is characterized by power-law distributions in the lifetime and size of fluctuating clusters. Experiments exhibit similar behavior and, as vs is reduced ...


Transition From N-Type To P-Type Destroys Ferromagnetism In Semiconducting Sn1-XCoXO2 And Sn1-XCrXO2 Nanoparticles, C. Van Komen, A. Punnoose, M. S. Seehra Dec 2009

Transition From N-Type To P-Type Destroys Ferromagnetism In Semiconducting Sn1-XCoXO2 And Sn1-XCrXO2 Nanoparticles, C. Van Komen, A. Punnoose, M. S. Seehra

Physics Faculty Publications and Presentations

This work reports strong correlations between the structural, magnetic and electronic properties of room temperature ferromagnets (RTFM) Sn1-xCoxO2 and Sn1-xCrxO2 for x = 0 to 0.1. The samples prepared by the sol-gel chemical method show RTFM for x < xL with the limiting concentration xL = 0.01 for Co doping and xL = 0.025 for Cr doping. As doping level x is increased from x = 0, the magnetic moment per ion, μ, increases and the lattice volume VL decreases up to x = xL. For x > x ...