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

Engineering Commons

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

Theses/Dissertations

2015

Purdue University

Physics

Articles 1 - 7 of 7

Full-Text Articles in Engineering

Modular Approach To Spintronics, Kerem Yunus Camsari Apr 2015

Modular Approach To Spintronics, Kerem Yunus Camsari

Open Access Dissertations

There has been enormous progress in the last two decades, effectively combining spintronics and magnetics into a powerful force that is shaping the field of memory devices. New materials and phenomena continue to be discovered at an impressive rate, providing an ever-increasing set of building blocks that could be exploited in designing transistor-like functional devices of the future. The objective of this thesis is to provide a quantitative foundation for this building block approach, so that new discoveries can be integrated into functional device concepts, quickly analyzed and critically evaluated. Through careful benchmarking against available theory and experiments we establish …


Experimental Constraints On Exotic Spin-Dependent Interactions Using Specialized Materials, Rakshya Khatiwada Apr 2015

Experimental Constraints On Exotic Spin-Dependent Interactions Using Specialized Materials, Rakshya Khatiwada

Open Access Dissertations

Various theories predict the possible existence of symmetry violating forces with mesoscopic range interactions from mm-m [1]. These forces can arise from the coupling of a spin 0 boson to spin 1/2 fermions through scalar (gs) and pseudoscalar (gp) couplings. We discuss two experiments that can investigate these interactions using nucleon rich, impressively low magnetic susceptibility (5-100 times lower than pure water) test masses and electron-spin rich, polarized test masses (spin density: 10^20 h/cm3 ). The first experiment looks for a P-odd, T-odd interaction potential proportional to (S.r) where S is the spin of one particle and r is the …


Transport Studies In Graphene-Based Materials And Structures, Jiuning Hu Apr 2015

Transport Studies In Graphene-Based Materials And Structures, Jiuning Hu

Open Access Dissertations

Graphene, a single atomic layer of graphite, has emerged as one of the most attractive materials in recent years for its many unique and excellent properties, inviting a broad area of fundamental studies and applications. In this thesis, we present some theoretical/experimental studies about the thermal, electronic and thermoelectric transport properties in graphene-based systems. We employ the molecular dynamic simulations to study the thermal transport in graphene nanoribbons (GNRs) exhibiting various properties, including chirality dependent thermal conductivity, thermal rectification in asymmetric GNRs, defects and isotopic engineering of the thermal conductivity and negative differential thermal conductance (NDTC) at large temperature biases. …


Computational Optical Imaging: Applications In Synthetic Aperture Imaging, Phase Retrieval, And Digital Holography, Dennis Joseph Lee Apr 2015

Computational Optical Imaging: Applications In Synthetic Aperture Imaging, Phase Retrieval, And Digital Holography, Dennis Joseph Lee

Open Access Dissertations

Computational imaging has become an important field, as a merger of both algorithms and physical experiments. In the realm of microscopy and optical imaging, an important application is the problem of improving resolution, which is bounded by wavelength and numerical aperture according to the classic diffraction limit. We will investigate the resolution enhancement of phase objects such as transparent biological cells. One key challenge is how to measure phase experimentally. Standard interferometric techniques have the drawback of being sensitive to environmental vibrations and temperature fluctuations, and they use a reference arm which requires more space and cost. Non-holographic methods provide …


Circular Bessel Field Statistics And The Pursuit Of Far-Subwavelength Resolution, Yulu Chen Apr 2015

Circular Bessel Field Statistics And The Pursuit Of Far-Subwavelength Resolution, Yulu Chen

Open Access Dissertations

The statistical description of wave propagation in random media is important for many applications. While polarized light in systems with weakly interacting scatterers and sufficient overall scatter has zero-mean circular Gaussian statistics, the underlying assumptions break down in the Anderson localization and weakly scattering regimes. Although probability density functions for wave intensity and amplitude exist beyond Gaussian statistics, suitable statistical descriptions for the field with strong and weak random scatter were unknown. The first analytical probability density function for the field that is effective in both the Anderson localization regime and the weakly scattering regime is derived by modeling the …


Growth Of Low Disorder Gaas/Algaas Heterostructures By Molecular Beam Epitaxy For The Study Of Correlated Electron Phases In Two Dimensions, John D. Watson Apr 2015

Growth Of Low Disorder Gaas/Algaas Heterostructures By Molecular Beam Epitaxy For The Study Of Correlated Electron Phases In Two Dimensions, John D. Watson

Open Access Dissertations

The unparalleled quality of GaAs/AlGaAs heterostructures grown by molecular beam epitaxy has enabled a wide range of experiments probing interaction effects in two-dimensional electron and hole gases. This dissertation presents work aimed at further understanding the key material-related issues currently limiting the quality of these 2D systems, particularly in relation to the fractional quantum Hall effect in the 2nd Landau level and spin-based implementations of quantum computation.^ The manuscript begins with a theoretical introduction to the quantum Hall effect which outlines the experimental conditions necessary to study the physics of interest and motivates the use of the semiconductor growth …


Novel Techniques For Quasi Three-Dimensional Nanofabrication Of Transformation Optics Devices, Paul R. West Jan 2015

Novel Techniques For Quasi Three-Dimensional Nanofabrication Of Transformation Optics Devices, Paul R. West

Open Access Dissertations

Current nanofabrication is almost exclusively limited to top-down, two-dimensional techniques. As technology moves more deeply into the nano-scale regime, fabrication of new devices with quasi three-dimensional geometries shows great potential. One excellent example of an emerging field that requires this type of non-conformal 3D fabrication technique is the field of Transformation Optics. This field involves transforming and manipulating the optical space through which light propagates. Arbitrarily manipulating the optical space requires advanced fabrication techniques, which are not possible with current two-dimensional fabrication technologies. One step toward quasi three-dimensional nanofabrication involves employing angled deposition allowing new growth mechanisms, and enabling a …