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Articles 1 - 11 of 11

Full-Text Articles in Physics

Time Reversal Invariance Violating And Parity Conserving Effects In Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov Aug 2011

Time Reversal Invariance Violating And Parity Conserving Effects In Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov

Faculty Publications

Time reversal invariance violating and parity conserving effects for low-energy elastic neutron-deuteronscattering are calculated for meson exchange and effective field theory type potentials in a distorted wave-bornapproximation using realistic hadronic wave functions, obtained by solving three-body Faddeev equations inconfiguration space.


Dynamics Of Spin Relaxation In Finite-Size Two-Dimensional Systems: An Exact Solution, Valeriy A. Slipko, Yuriy V. Pershin Aug 2011

Dynamics Of Spin Relaxation In Finite-Size Two-Dimensional Systems: An Exact Solution, Valeriy A. Slipko, Yuriy V. Pershin

Faculty Publications

We find an exact solution for the problem of electron spin relaxation in a two-dimensional (2D) circle with Rashba spin-orbit interaction. Our analysis shows that the spin relaxation in finite-size regions involves three stages and is described by multiple spin relaxation times. It is important that the longest spin relaxation time increases with the decrease in system radius but always remains finite. Therefore, at long times, the spin polarization in small 2D systems decays exponentially with a size-dependent rate. This prediction is supported by results of Monte Carlo simulations.


Time Reversal Invariance Violation In Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov Jun 2011

Time Reversal Invariance Violation In Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov

Faculty Publications

Time reversal invariance-violating (TRIV) effects in low-energy elastic neutron-deuteron scattering arecalculated using meson exchange and EFT-type TRIV potentials in a distorted-wave Born approximation withrealistic hadronic strong interaction wave functions, obtained by solving the three-body Faddeev equations inconfiguration space. The relation between TRIV and parity-violating observables is discussed.


Growth Direction Modulation And Diameter-Dependent Mobility In Inn Nanowires, Goutam Koley, Zhihua Cai, Ehtesham Bin Quddus, Jie Liu, Muhammad Qazi, Richard A. Webb Jun 2011

Growth Direction Modulation And Diameter-Dependent Mobility In Inn Nanowires, Goutam Koley, Zhihua Cai, Ehtesham Bin Quddus, Jie Liu, Muhammad Qazi, Richard A. Webb

Faculty Publications

Diameter-dependent electrical properties of InN nanowires (NWs) grown by chemical vapor deposition have been investigated. The NWs exhibited interesting properties of coplanar deflection at specific angles, either spontaneously, or when induced by other NWs or lithographically patterned barriers. InN NW-based back-gated field effect transistors (FETs) showed excellent gate control and drain current saturation behaviors. Both NW conductance and carrier mobility calculated from the FET characteristics were found to increase regularly with a decrease in NW diameter. The observed mobility and conductivity variations have been modeled by considering NW surface and core conduction paths.


Spontaneous Emergence Of A Persistent Spin Helix From Homogeneous Spin Polarization, Valeriy A. Slipko, Ibrahim Savran, Yuriy V. Pershin Dr May 2011

Spontaneous Emergence Of A Persistent Spin Helix From Homogeneous Spin Polarization, Valeriy A. Slipko, Ibrahim Savran, Yuriy V. Pershin Dr

Faculty Publications

We demonstrate that a homogeneous spin polarization in one-dimensional structures of finite length in the presence of Bychkov-Rashba spin-orbit coupling decays spontaneously toward a persistent spin helix. Such a strikingly different and simple method enables us to generate robust spin structures whose properties can be tuned by the strength of the spin-orbit interaction and/or the structure’s length. We generalize our results for the two-dimensional case predicting the formation of a persistent spin helix in two-dimensional channels from homogeneous spin polarization. An analysis of the formation of a spin helical state is presented within an approach based on a ...


Parametric Resonance Enhancement In Neutron Interferometry And Application For The Search For Non-Newtonian Gravity, Vladimir Gudkov, Hirohiko M. Shimizu, Geoffrey L. Greene Feb 2011

Parametric Resonance Enhancement In Neutron Interferometry And Application For The Search For Non-Newtonian Gravity, Vladimir Gudkov, Hirohiko M. Shimizu, Geoffrey L. Greene

Faculty Publications

The parametric resonance enhancement of the phase of neutrons due to non-Newtonian anomalous gravitationis considered. The existence of such resonances is confirmed by numerical calculations. A possible experimentalscheme for observing this effect is discussed based on an existing neutron interferometer design.


Parity Violation In Low-Energy Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov Jan 2011

Parity Violation In Low-Energy Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov

Faculty Publications

Parity-violating effects for low-energy elastic neutron deuteron scattering are calculated for Desplanques,Donoghue, and Holstein (DDH) and effective field theory types of weak potentials in a distorted-wave Bornapproximation, using realistic hadronic strong interaction wave functions, obtained by solving three-bodyFaddeev equations in configuration space. The resulting relation between physical observables and low-energyconstants can be used to fix low-energy constants from experiments. Potential model dependencies ofparity-violating effects are discussed.


Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason R. Hattrick-Simpers, Wilbur S. Hurst, Sesha S. Srinivasan, James E. Maslar Jan 2011

Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason R. Hattrick-Simpers, Wilbur S. Hurst, Sesha S. Srinivasan, James E. Maslar

Faculty Publications

An optical cell is described for high-throughput backscattering Raman spectroscopic measurements of hydrogen storagematerials at pressures up to 10 MPa and temperatures up to 823 K. High throughput is obtained by employing a 60 mm diameter × 9 mm thick sapphire window, with a corresponding 50 mm diameter unobstructed optical aperture. To reproducibly seal this relatively large window to the cell body at elevated temperatures and pressures, a gold o-ring is employed. The sample holder-to-window distance is adjustable, making this cell design compatible with optical measurement systems incorporating lenses of significantly different focal lengths, e.g., microscope objectives and single element ...


Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, S. Suthirakun, Salai Cheettu Ammal, G. Xiao, Fanglin Chen, Hans-Conrad Zur Loye, Andreas Heyden Jan 2011

Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, S. Suthirakun, Salai Cheettu Ammal, G. Xiao, Fanglin Chen, Hans-Conrad Zur Loye, Andreas Heyden

Faculty Publications

The electronic conductivity and thermodynamic stability of mixed n-type and p-type doped SrTiO3 have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb- and Ga-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to study the effects of n- and p-doping on the electronic conductivity. In agreement with experimental observations, we find that the transformation from 20% Nb-doped Sr-deficient SrTiO3 to a non-Sr-deficient phase ...


Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, S. Kewalramani, S. Wang, Y. Lin, H. G. Nguyen, Qian Wang, M. Fukuto, L. Yang Jan 2011

Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, S. Kewalramani, S. Wang, Y. Lin, H. G. Nguyen, Qian Wang, M. Fukuto, L. Yang

Faculty Publications

We report an experimental demonstration of a strategy for inducing two-dimensional (2D)crystallization of charged nanoparticles on oppositely charged fluid interfaces. This strategy aims to maximize the interfacial adsorption of nanoparticles, and hence their lateral packing density, by utilizing a combination of weakly charged particles and a high surface charge density on the planar interface. In order to test this approach, we investigated the assembly of cowpea mosaic virus (CPMV) on positively charged lipid monolayers at the aqueous solution surface, by means of in situX-ray scattering measurements at the liquid–vapor interface. Theassembly was studied as a function of ...


Efficient Quantum Trajectory Representation Of Wavefunctions Evolving In Imaginary Time, Sophya V. Garashchuk, J. Mazzuca, T. Vazhappilly Jan 2011

Efficient Quantum Trajectory Representation Of Wavefunctions Evolving In Imaginary Time, Sophya V. Garashchuk, J. Mazzuca, T. Vazhappilly

Faculty Publications

The Boltzmann evolution of a wavefunction can be recast as imaginary-time dynamics of the quantum trajectory ensemble. The quantum effects arise from the momentum-dependent quantum potential – computed approximately to be practical in high-dimensional systems – influencing the trajectories in addition to the external classical potential [S. Garashchuk, J. Chem. Phys.132, 014112 (2010)]. For a nodelesswavefunction represented as ψ(x, t) = exp ( −S(x, t)/ℏ) with the trajectory momenta defined by ∇S(x, t), analysis of the Lagrangian and Eulerian evolution shows that for bound potentials the former is more accurate while the latter is more practical because the Lagrangian ...