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

Digital Commons Network™

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

Physics

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 29701 - 29730 of 34166

Full-Text Articles in Entire DC Network

Long-Range Order And Magnetic Properties Of MnXPt1 – X Thin Films, Kurt W. Wierman, Roger D. Kirby Mar 1996

Long-Range Order And Magnetic Properties Of MnXPt1 – X Thin Films, Kurt W. Wierman, Roger D. Kirby

Roger Kirby Publications

Thin films of MnxPt1–x (x = 0.18, 0.22, 0.25, 0.30, 0.34) were prepared by magnetron sputtering onto quartz substrates. After annealing in vacuum for 1 h at 850°C, X-ray diffraction indicates that the films have the Cu3Au cubic structure (a = 3.87 Å) and are highly textured with the (111) axis along the film normal. These samples have a high degree of long-range order, as indicated by the ratio of the intensities of the superlattice (100) and fundamental (200) X-ray diffraction reflections. We report here the results of magnetic and magnetooptical measurements …

Go to article

Linear And Non-Linear Preprocessing Of Wavefront Sensor Slope Measurements For Improved Adaptive Optics Performance, Dennis A. Montera Mar 1996

Linear And Non-Linear Preprocessing Of Wavefront Sensor Slope Measurements For Improved Adaptive Optics Performance, Dennis A. Montera

Theses and Dissertations

New methods for preprocessing wavefront sensor (WFS) slope measurements are presented. Methods are developed to improve the accuracy of WFS slope measurements, as well as estimating key atmospheric and system parameters from the slope signals. Both statistical and artificial neural network solutions are investigated. Also, new atmospheric models for generating slope and phase data with the proper spatial and temporal statistics are developed. The experiments in improving the accuracy of WFS slope measurements include reducing the WFS slope measurement error and compensating for adaptive optics system time delay through temporal slope prediction. The experiments in key parameter estimation include estimating …

Go to article

A Statistical Study Of Transient Events In The Outer Dayside Magnetosphere, Jeff Sanny, D. G. Sibeck, C. C. Venturini, C. T. Russell Mar 1996

A Statistical Study Of Transient Events In The Outer Dayside Magnetosphere, Jeff Sanny, D. G. Sibeck, C. C. Venturini, C. T. Russell

Physics Faculty Works

The AMPTE CCE satellite frequently observed transient (1 ≤ τ ≤ 8 min) events marked by magnetic field strength increases and bipolar magnetic field signatures (peak-to-peak amplitudes ≥ 4 nT) while in the outer dayside magnetosphere. We report a survey of 59 prominant events observed from August to November 1984. The bipolar signatures and minimum variance analysis reveal that most events move poleward and antisunward, except in the immediate vicinity of local noon. Here the motion of the events appears to be better governed by the spiral/orthospiral interplanetary magnetic field (IMF) orientation than magnetic curvature forces associated with IMF By. …

Go to article

Signal Averaging X-Ray Streak Camera With Picosecond Jitter, Anatoly Maksimchuk, M. Kim, J. Workman, G. Korn, J. Squier, D. Du, Donald Umstadter, G. Mourou, M. Bouvier Mar 1996

Signal Averaging X-Ray Streak Camera With Picosecond Jitter, Anatoly Maksimchuk, M. Kim, J. Workman, G. Korn, J. Squier, D. Du, Donald Umstadter, G. Mourou, M. Bouvier

Donald Umstadter Publications

We have developed an averaging picosecond x-ray streak camera using a dc-biased photoconductive switch as a generator of a high-voltage ramp. The streak camera is operated at a sweep speed of up to 8 ps/mm, shot-to-shot jitter is less than ±1 ps. The streak camera has been used to measure the time history of broadband x-ray emission from an ultrashort pulse laser-produced plasma. Accumulation of the streaked x-ray signals significantly improved the signal-to-noise ratio of the data obtained.

Go to article

Optical Electron Polarimetry With Heavy Noble Gases, Timothy J. Gay, J. E. Furst, K. W. Trantham, W. M. K. P. Wijayaratna Mar 1996

Optical Electron Polarimetry With Heavy Noble Gases, Timothy J. Gay, J. E. Furst, K. W. Trantham, W. M. K. P. Wijayaratna

Timothy J. Gay Publications

We have measured the polarization of fluorescence emitted by the noble gases He, Ne, Ar, Kr, and Xe following impact excitation by polarized electrons. In He, the 33P→23S transition was studied; in the heavy noble gases the np5 (n+1) p 3D3→np5 (n+1) s3P2 transitions were analyzed. We investigated these transitions as candidates for efficient optical electron polarimetry and found that, because of their larger excitation cross sections and analyzing power, the heavy noble gases are superior to He, which had been used …

Go to article

A Magnetic Neutron Diffraction, And Mössbauer Spectral Study Of The Ce₂Fe₁₇₋ₓalₓ Solid Solutions, Sanjay R. Mishra, Gary J. Long, Oran Allan Pringle, D. P. Middleton, Zhongbo Hu, William B. Yelon, Fernande Grandjean, K. H. J. Buschow Mar 1996

A Magnetic Neutron Diffraction, And Mössbauer Spectral Study Of The Ce₂Fe₁₇₋ₓalₓ Solid Solutions, Sanjay R. Mishra, Gary J. Long, Oran Allan Pringle, D. P. Middleton, Zhongbo Hu, William B. Yelon, Fernande Grandjean, K. H. J. Buschow

Chemistry Faculty Research & Creative Works

The magnetic properties of a series of Ce2Fe17-xAlx solid solutions with x equal to 0.00, 0.88, 2.06, 2.81, 3.98, 5.15, 6.08, 7.21, 8.20, 9.08, 9.84, and 10.62 have been studied by magnetic measurements, neutron diffraction, and Mössbauer spectroscopy. The compounds crystallize in the rhombohedral Th2Zn17-type structure. Magnetization studies indicate that the Curie temperature increases uniformly from 238 K for Ce2Fe17 to 384 K for Ce2Fe14Al3 and then decreases at higher aluminum content. Powder neutron diffraction results, obtained at 295 K, indicate that aluminum …

Go to article

Spectroscopy Of Atoms Confined To The Single Node Of A Standing Wave In A Parallel-Plate Cavity, V. Sandoghar, C. I. Sukenik, S. Haroche, E. A. Hinds Mar 1996

Spectroscopy Of Atoms Confined To The Single Node Of A Standing Wave In A Parallel-Plate Cavity, V. Sandoghar, C. I. Sukenik, S. Haroche, E. A. Hinds

Physics Faculty Publications

We have performed spectroscopy on sodium atoms that are optically channeled in the single node of a laser standing wave set up across a parallel-plate cavity. Using this technique we have extended our previous measurement of the Lennard-Jones van der Waals energy-level shift [Sandoghdar et al., Phys. Rev. Lett. 68, 3432 (1992)] down to a cavity width of ~500 nm. We discuss the applications of this technique to the precise measurement of atom-surface distances.

Go to article

Tabletop Laser Accelerators Are On The Way, Phillip F. Schewe, Ben Stein, Donald P. Umstadter Feb 1996

Tabletop Laser Accelerators Are On The Way, Phillip F. Schewe, Ben Stein, Donald P. Umstadter

Donald Umstadter Publications

The goal here is to use high electric fields in plasmas to accelerate electrons to 100-GeV energies over distances of meters rather than kilometers. This should promote the development of new particle colliders and x-ray sources. The predicted high acceleration gradients in plasmas have been achieved in recent years, but could only be used with external electron injection from a conventional source. Now scientists at the University of Michigan (Donald Umstadter, 313-764-2284) have made progress in eliminating conventional electron sources altogether. In a preliminary experiment, by simply focusing a laser into a plasma, the Michigan scientists have extracted a collimated …

Go to article

Ultraviolet And Electron Radiation Induced Fragmentation Of Adsorbed Ferrocene, Dulip Welipitiya, A. Green, J.P. Woods, Peter A. Dowben, Brian W. Robertson, Dongjin Byun, Jiandi Zhang Feb 1996

Ultraviolet And Electron Radiation Induced Fragmentation Of Adsorbed Ferrocene, Dulip Welipitiya, A. Green, J.P. Woods, Peter A. Dowben, Brian W. Robertson, Dongjin Byun, Jiandi Zhang

Peter Dowben Publications

From thermal desorption spectroscopy we find that ferrocene, Fe(C5H5)2, adsorbs and desorbs associatively on Ag(100). Photoemission results indicate that the initially adsorbed surface species closely resembles that of molecular ferrocene. The shift in photoemission binding energies relative to the gas phase is largely independent of the molecular orbital. We find that ultraviolet light does lead to partial fragmentation of the ferrocene and that the molecular fragments are much more strongly bound to the surface than the associatively adsorbed ferrocene. Since fragmentation occurs only in the presence of incident radiation, selective area deposition from this …

Go to article

New Model For Electron-Impact Ionization Cross Sections Of Molecules, W. Hwang, Y.-K. Kim, M. Eugene Rudd Feb 1996

New Model For Electron-Impact Ionization Cross Sections Of Molecules, W. Hwang, Y.-K. Kim, M. Eugene Rudd

M. Eugene Rudd Publications

A theoretical model for electron-impact ionization cross sections, which has been developed primarily for atoms and atomic ions, is applied to neutral molecules. The new model combines the binary-encounter theory and the Bethe theory for electron-impact ionization, and uses minimal theoretical data for the ground state of the target molecule, which are readily available from public-domain molecular structure codes such as GAMESS. The theory is called the binary encounter Bethe (BEB) model, and does not, in principle, involve any adjustable parameters. Applications to 19 molecules, including H2, NO, CH2, C6H6, and SF …

Go to article

Consequences Of Supergravity With Gauged U(1)R Symmetry, Diego Castano, D. Z. Freedman, C. Manuel Feb 1996

Consequences Of Supergravity With Gauged U(1)R Symmetry, Diego Castano, D. Z. Freedman, C. Manuel

Chemistry and Physics Faculty Articles

The structure of gauged R-supergravity Lagrangians is reviewed, and we consider models with a hidden sector plus light fields of the MSSM. A simple potential for the hidden sector is presented which has a global minimum with zero cosmological constant and spontaneously broken SUSY and R-symmetry. The U(1)R vector multiplet acquires a Planck scale through the Higgs mechanism, and it decouples at low energy. Due to very interesting cancellations, the U(1)RD-terms also drop out at low energy. Thus no direct effects of the gauging of R-symmetry remain in the low-energy effective Lagrangian, …

Go to article

C-Axis Oriented (Hg,Ti)-Based Superconducting Films With TC≥125 K, F. Foong, B. Bedard, Q.L. Xu, Sy_Hwang Liou Feb 1996

C-Axis Oriented (Hg,Ti)-Based Superconducting Films With TC≥125 K, F. Foong, B. Bedard, Q.L. Xu, Sy_Hwang Liou

Sy-Hwang Liou Publications

Thin films with mostly (Hg,Tl) 1Ba2Ca3Cu2O8+ δ [(Hg,Tl)-1223] phase have been fabricated by radio frequency magnetron sputtering of precursor films and post-annealing method. The doping of a small amount of thallium in the film is helpful to the formation of the three-layer CuO2 compound. These films have a highly oriented structure with the c-axis perpendicular to the film surface. Resistivity measurements show that the films after annealing at 300 °C for 1 h in O2 have the superconducting transition temperature of Tc (onset)=133 K and Tc (zero)=127 …

Go to article

Rapidity Gaps Between Jets In Photoproduction At Hera, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, R. Bruni, G. Cara Romeo, G. Castellini, M. Chiarini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, R. Giusti, G. Iacobucci, G. Laurenti, G. Levi, A. Margotti, T. Massam, R. Nania, Margarita C. K. Mattingly Feb 1996

Rapidity Gaps Between Jets In Photoproduction At Hera, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, R. Bruni, G. Cara Romeo, G. Castellini, M. Chiarini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, R. Giusti, G. Iacobucci, G. Laurenti, G. Levi, A. Margotti, T. Massam, R. Nania, Margarita C. K. Mattingly

Faculty Publications

Photoproduction events which have two or more jets have been studied in the Wγp range 135 GeV < Wγp < 280 GeV with the ZEUS detector at HERA. A class of events is observed with little hadronic activity between the jets. The jets are separated by pseudorapidity intervals (Δη) of up to four units and have transverse energies greater than 6 GeV. A gap is defined as the absence between the jets of particles with transverse energy greater than 300 MeV. The fraction of events containing a gap is measured as a function of Δη. It decreases exponentially as expected for processes in which colour is exchanged between the jets, up to a value of Δη ∼ 3, then reaches a constant value of about 0.1. The excess above the exponential fall-off can be interpreted as evidence for hard diffractive scattering via a strongly interacting colour singlet object.

Go to article

Evidence Favoring Molybdenum−Carbon Bond Formation In Xanthine Oxidase Action: 17O- And 13C-Endor And Kinetic Studies, Barry D. Howes, Robert C. Bray, Raymond L. Richards, Nigel A. Turner, Brian Bennett, David J. Lowe Feb 1996

Evidence Favoring Molybdenum−Carbon Bond Formation In Xanthine Oxidase Action: 17O- And 13C-Endor And Kinetic Studies, Barry D. Howes, Robert C. Bray, Raymond L. Richards, Nigel A. Turner, Brian Bennett, David J. Lowe

Physics Faculty Research and Publications

The reaction mechanism of the molybdoenzyme xanthine oxidase has been further investigated by 13C and 17O ENDOR of molybdenum(V) species and by kinetic studies of exchange of oxygen isotopes. Three EPR signal-giving species were studied:  (i) Very Rapid, a transient intermediate in substrate turnover, (ii) Inhibited, the product of an inhibitory side reaction with aldehyde substrates, and (iii) Alloxanthine, a species formed by reaction of reduced enzyme with the inhibitor, alloxanthine. The Very Rapid signal was developed either with [8-13C]xanthine or with 2-oxo-6-methylpurine using enzyme equilibrated with [17O]H2O. The Inhibited signal was …

Go to article

Photodetachment Of Li- From The Li 3S Threshold To The Li 6S Threshold, Cheng Pan, Anthony F. Starace, Chris H. Greene Feb 1996

Photodetachment Of Li- From The Li 3S Threshold To The Li 6S Threshold, Cheng Pan, Anthony F. Starace, Chris H. Greene

Anthony F. Starace Publications

Eigenchannel R-matrix calculations (including effects of long-range multipole interactions beyond the reaction volume) for Li- photodetachment partial cross sections from the vicinity of the Li 3s threshold to the Li 6s threshold (3.8 eV ≤ħω≤ 5.65 eV) are presented. Excellent agreement with the relative total cross section measurements of U. Berzinsh et al. [Phys. Rev. Lett. 74, 4795 (1995)] in the vicinity of the Li 3s and Li 3p thresholds is found. The calculated resonance structures are analyzed in detail. In particular, the energy region between the Li 4s and Li 5 …

Go to article

Fluctuations And Light Scattering In A Liquid Crystal Polymer Fiber, R. A. Sones, Rolfe G. Petschek Feb 1996

Fluctuations And Light Scattering In A Liquid Crystal Polymer Fiber, R. A. Sones, Rolfe G. Petschek

Faculty Scholarship

The spatial correlation function is calculated for thermal fluctuations of the liquid crystal director field in the core of an optical fiber composed of a main chain liquid crystal polymer in the smectic-C phase. Due to steric constraints on the liquid crystal polymer, the smectic layers orient perpendicular to the fiber axis, the liquid crystal director lies flat against the core-cladding interface, and a line disclination appears along the fiber axis. The analysis is based on a Landau-de Gennes expression for free energy, which includes ordinary smectic-C elastic terms as well as terms added to model the disclination. The correlation …

Go to article

Response To ‘‘Comment On ‘A Paradox Involving The Second Law Of Thermodynamics’ ’’ [Phys. Plasmas 2, 1893 (1995)], D. P. Sheehan Feb 1996

Response To ‘‘Comment On ‘A Paradox Involving The Second Law Of Thermodynamics’ ’’ [Phys. Plasmas 2, 1893 (1995)], D. P. Sheehan

Physics and Biophysics: Faculty Scholarship

No abstract provided.

Go to article

High Density Qcd With Static Quarks, James E. Hetrick, T. Blum, D. Toussaint Feb 1996

High Density Qcd With Static Quarks, James E. Hetrick, T. Blum, D. Toussaint

All Faculty Articles - School of Engineering and Computer Science

We study lattice QCD in the limit that the quark mass and chemical potential are simultaneously made large, resulting in a controllable density of quarks which do not move. This is similar in spirit to the quenched approximation for zero density QCD. In this approximation we find that the deconfinement transition seen at zero density becomes a smooth crossover at very small density (possibly for any nonzero density), and that at low enough temperature chiral symmetry remains broken at all densities.

Go to article

Low Energy Electron Scattering From Ch3Cl, X. Shi, V.K. Chan, Gordon A. Gallup, Paul Burrow Feb 1996

Low Energy Electron Scattering From Ch3Cl, X. Shi, V.K. Chan, Gordon A. Gallup, Paul Burrow

Paul Burrow Publications

Differential cross section measurements for the elastic scattering of electrons from CH3Cl at energies from 0.5 to 9.5 eV are reported for scattering angles of 30° and 100°. The angular scattering dependence is determined at selected energies over this range. At energies below 1.0 eV, the cross sections are in excellent agreement with calculations using the Born dipole approximation. At large angles and higher energies, the scattering is dominated by a 2A1 temporary negative ion state near 3.5 eV. Energy loss data at 3.5, 5.0, and 8.5 eV are reported and the relative contributions of various …

Go to article

Heat-Capacity And Magnetic Measurements On The Y(Ni2-XCoX)B2C System, C. C. Hoellwarth, P. Klavins, R. N. Shelton Feb 1996

Heat-Capacity And Magnetic Measurements On The Y(Ni2-XCoX)B2C System, C. C. Hoellwarth, P. Klavins, R. N. Shelton

Physics

We have performed field-and temperature-dependent magnetization, resistivity, and heat-capacity measurements on polycrystalline samples of the Y(Ni2-xCox)B2C system with 0.0≤x≤0.4. Values of Tc ,x0,Hc2,ΘD,λ and N(Ed) were determined for various samples. We observe that ΘD increases with x, while all the other parameters decrease with x. The Tc vs x data can be described using the BCS theory and the measured values of N(Ef)and ΘD. The results suggest that the decrease in Tc is due to the decrease in …

Go to article

Investigation Of Potential Oxygen Defect Mechanism Of Persistent Photoconductivity And Photoinduced Superconductivity In Yba2cu3ox, Denise Catherine Chew Jan 1996

Investigation Of Potential Oxygen Defect Mechanism Of Persistent Photoconductivity And Photoinduced Superconductivity In Yba2cu3ox, Denise Catherine Chew

Theses

In this thesis work, we conclude that oxygen vacancy defects play a fundamental role in the PPC/PISC mechanism and identify the oxygen defects as F centers (an oxygen vacancy which traps two electrons) or F+ centers. Also, the correlation between the peaks observed in the luminescence spectra and those observed in the wavelength dependence of PPC suggest that the photogeneration of charges and their annihilation via luminescent recombination occur in the same level (Cu-O chains) of the YBa2Cu3Ox crystal. Previous models had assigned the peaks in the PPC excitation spectrum to charge transfer in …

Go to article

The Genetic Algorithm And Maximum Entropy Dice, Laura Suzanne Fellman Jan 1996

The Genetic Algorithm And Maximum Entropy Dice, Laura Suzanne Fellman

Dissertations and Theses

The Brandeis dice problem, originally introduced in 1962 by Jaynes as an illustration of the principle of maximum entropy, was solved using the genetic algorithm, and the resulting solution was compared with that obtained analytically. The effect of varying the genetic algorithm parameters was observed, and the optimum values for population size, mutation rate, and mutation interval were determined for this problem. The optimum genetic algorithm program was then compared to a completely random method of search and optimization. Finally, the genetic algorithm approach was extended to several variations of the original problem for which an analytical approach would be …

Go to article

The Vacuum In Light Cone Field Theory, David G. Robertson Jan 1996

The Vacuum In Light Cone Field Theory, David G. Robertson

Physics Faculty Scholarship

This is an overview of the problem of the vacuum in light-cone field theory, stressing its close connection to other puzzles regarding light-cone quantization. I explain the sense in which the light-cone vacuum is ``trivial,'' and describe a way of setting up a quantum field theory on null planes so that it is equivalent to the usual equal-time formulation. This construction is quite helpful in resolving the puzzling aspects of the light-cone formalism. It furthermore allows the extraction of effective Hamiltonians that incorporate vacuum physics, but that act in a Hilbert space in which the vacuum state is simple. The …

Go to article

Ray Scattering By An Arbitrarily Oriented Spheroid .I. Diffraction And Specular Reflection, James A. Lock Jan 1996

Ray Scattering By An Arbitrarily Oriented Spheroid .I. Diffraction And Specular Reflection, James A. Lock

Physics Faculty Publications

Diffraction and reflection of an arbitrarily polarized plane wave by an arbitrarily oriented spheroid in the short-wavelength limit are considered in the context of ray theory. A closed-form solution for both diffraction and reflection is obtained, and the polarization character of the diffracted plus reflected electric field is obtained. It is found that the magnitude of the reflected electric field is multivalued for forward scattering. This is interpreted in terms of the variation of the spheroid's Gaussian curvature at the points where grazing ray incidence occurs.

Go to article

Ray Scattering By An Arbitrarily Oriented Spheroid .Ii. Transmission And Cross-Polarization Effects, James A. Lock Jan 1996

Ray Scattering By An Arbitrarily Oriented Spheroid .Ii. Transmission And Cross-Polarization Effects, James A. Lock

Physics Faculty Publications

Transmission of an arbitrarily polarized plane wave by an arbitrarily oriented spheroid in the short-wavelength limit is considered in the context of ray theory. The transmitted electric field is added to the diffracted plus reflected ray-theory electric field that was previously derived to obtain an approximation to the far-zone scattered intensity in the forward hemisphere. Two different types of cross-polarization effects are found. These are (a) a rotation of the polarization state of the transmitted rays from when they are referenced with respect to their entrance into the spheroid to when they are referenced with respect to their exit from …

Go to article

Polarization Of Astronomical Maser Radiation. Iii. Arbitrary Zeeman Splitting And Anisotropic Pumping, Moshe Elitzur Jan 1996

Polarization Of Astronomical Maser Radiation. Iii. Arbitrary Zeeman Splitting And Anisotropic Pumping, Moshe Elitzur

Physics and Astronomy Faculty Publications

General solutions of the maser polarization problem are presented for arbitrary absorption coefficients. The results are used to calculate polarization for masers permeated by magnetic fields with arbitrary values of χB, the ratio of Zeeman splitting to Doppler linewidth, and for anisotropic (m-dependent) pumping. In the case of magnetic fields, one solution describes the polarization for overlapping Zeeman components, χB < 1. The χB → 0 limit of this solution reproduces the linear polarization derived in previous studies, which were always conducted at this unphysical limit. Terms of higher order in χB have a negligible effect on …

Go to article

Fabrication Of Boron-Carbide Boron Heterojunction Devices, Seong-Don Hwang, Dongjin Byun, N.J. Ianno, Peter A. Dowben, H.R. Kim Jan 1996

Fabrication Of Boron-Carbide Boron Heterojunction Devices, Seong-Don Hwang, Dongjin Byun, N.J. Ianno, Peter A. Dowben, H.R. Kim

Peter Dowben Publications

We have succeeded in the fabrication of a boron–carbide/boron diode on an aluminum substrate, and a boron–carbide/boron junction field effect transistor. Our results suggest that with respect to the approximately 2 eV band gap pure boron material, 0.9 eV band gap boron–carbide (B5C) acts as a p-type material. Both boron and boron–carbide (B5C) thin films were fabricated from single source borane cage molecules using plasma enhanced chemical vapor deposition (PECVD). Epitaxial growth does not appear to be a requirement. ©1996 American Institute of Physics.

Go to article

The Possibility Of Flux Flow Spectroscopy, S. E. Barnes, J. L. Cohn, F. Zuo Jan 1996

The Possibility Of Flux Flow Spectroscopy, S. E. Barnes, J. L. Cohn, F. Zuo

Physics Articles and Papers

A novel spectroscopic technique applicable to the study of spin excitations in magnetic materials is described. The probe frequency and wave vector are determined by the moving Abrikosov flux lattice of a type II superconductor in the mixed state. The feasibility of employing oxide superconductors and relevant material parameters are discussed.

Go to article

Oblique Electron Transport In The Presence Of Collinear And Noncollinear Magnetizations, Horacio E. Camblong Jan 1996

Oblique Electron Transport In The Presence Of Collinear And Noncollinear Magnetizations, Horacio E. Camblong

Physics and Astronomy

The nonlocal real‐space Kubo approach to electron transport in magnetic multilayers is applied to a new geometry, ‘‘oblique transport,’’ whose complexity is traced back to a combination of the layering, of the nonlocal character of the linear response, and of the oblique direction transport in this new geometry. The problem is dealt with by applying a condition on the average current density vector or on the average electric‐field vector, depending upon the external driving conditions. Its solution exhibits a characteristic anisotropy and it yields the global oblique conductance and magnetoresistance as simple trigonometric expressions in terms of the in‐plane and …

Go to article

Equilibrium Structure And Bonding Of Small Iron-Carbon Clusters, Beth K. Nash, B. K. Rao, Puru Jena Jan 1996

Equilibrium Structure And Bonding Of Small Iron-Carbon Clusters, Beth K. Nash, B. K. Rao, Puru Jena

Physics Publications

The equilibrium geometries, binding energies, and electronic structure of neutral FeC n (n≤3) clusters have been calculated self‐consistently using ab initio molecular orbital theory. The exchange and correlation contributions to the total energy were computed using both the density functional method (with and without nonlocal correction) as well as the Hartree–Fock–Möller–Plesset theory. All levels of theory predict the equilibrium geometries to be cyclic. The binding energies, bond lengths, and the Mulliken charges obtained from both methods of calculations are also in agreement. The results are compared with recent mobility and photoelectron spectroscopy experiments.

Go to article

First Prev Next Last