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Physics

University of Nebraska - Lincoln

2006

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Articles 31 - 60 of 147

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Surface Segregation In Multicomponent Clusters, Peter A. Dowben, Ning Wu, Natalie Palina, R. Müller, J. Hormes, Yaroslav B. Losovyj Oct 2006

Surface Segregation In Multicomponent Clusters, Peter A. Dowben, Ning Wu, Natalie Palina, R. Müller, J. Hormes, Yaroslav B. Losovyj

Peter Dowben Publications

Nanostructured materials are not immune from surface segregation, as can be shown for solid samples made from nanosized BaFe12–2xCoxTixO19 barium ferrite particles and a variety of free clusters. Both theory and experiment provide ample demonstration that very limited dimensions of very small clusters does not necessarily impart stability against surface and grain boundary segregation. In fact, with the larger surface to volume ratio in small clusters and lower average atomic coordination, we anticipate that compositional instabilities in small clusters will readily occur.

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Hubble Space Telescope Ultraviolet Spectroscopy Of Fourteen Low-Redshift Quasars, Rajib Ganguly, Michael S. Brotherton, Nahum Arav, Sara R. Heap, Lutz Wisotzki, Thomas L. Aldcroft, Danielle Alloin, Ehud Behar, Gabriela Canalizo, D. Michael Crenshaw, Martijn De Kool, Kenneth Chambers, Gerald Cecil, Eleni Chatzichristou, John Everett, Jack R. Gabel, C. Martin Gaskell, Emmanuel Galliano, Richard F. Green, Patrick B. Hall, Dean C. Hines, Vesa T. Junkkarinen, Jelle S. Kaastra, Mary Elizabeth Kaiser, Demosthenes Kazanas, Arieh Konigl, Kirk T. Korista, Gerard A. Kriss, Ari Laor, Karen M. Leighly, Smita Mathur, Patrick Ogle, Daniel Ogle, Bassem Sabra, Ran Sivron, Stephanie A. Snedden, Randal Telfer, Marianne Vestergaard Oct 2006

Hubble Space Telescope Ultraviolet Spectroscopy Of Fourteen Low-Redshift Quasars, Rajib Ganguly, Michael S. Brotherton, Nahum Arav, Sara R. Heap, Lutz Wisotzki, Thomas L. Aldcroft, Danielle Alloin, Ehud Behar, Gabriela Canalizo, D. Michael Crenshaw, Martijn De Kool, Kenneth Chambers, Gerald Cecil, Eleni Chatzichristou, John Everett, Jack R. Gabel, C. Martin Gaskell, Emmanuel Galliano, Richard F. Green, Patrick B. Hall, Dean C. Hines, Vesa T. Junkkarinen, Jelle S. Kaastra, Mary Elizabeth Kaiser, Demosthenes Kazanas, Arieh Konigl, Kirk T. Korista, Gerard A. Kriss, Ari Laor, Karen M. Leighly, Smita Mathur, Patrick Ogle, Daniel Ogle, Bassem Sabra, Ran Sivron, Stephanie A. Snedden, Randal Telfer, Marianne Vestergaard

C. Martin Gaskell Publications

We present low-resolution ultraviolet spectra of 14 low redshift (z em < 0.8) quasars observed with HST/STIS as part of a Snap project to understand the relationship between quasar outflows and luminosity. By design, all observations cover the C IV emission line. Nine of the quasars are from the Hamburg-ESO catalog, three are from the Palomar-Green catalog, and one is from the Parkes catalog. The sample contains a few interesting quasars including two broad absorption line (BAL) quasars (HE 0143- 3535, HE0436-2614), one quasar with a mini-BAL (HE 1105-0746), and one quasar with associated narrow absorption (HE 0409-5004). These BAL quasars are among the brightest known (though not the most luminous) since they lie at z em< 0.8. We compare the properties of these BAL quasars to the z em < 0.5 Palomar-Green and z em> 1.4 Large Bright Quasar samples. By design, our objects sample luminosities in between these two surveys, and our four absorbed objects are consistent with the υ ∼L 0.62 relation derived by Laor & Brandt (2002). Another quasar, HE0441-2826, contains extremely weak emission lines and our spectrum is consistent with a simple power- law continuum. The quasar is radio-loud, but has a steep spectral index and a lobe- dominated morphology, which argues against it being a blazar. The unusual spectrum of this …

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Search For Associated Higgs Boson Production Wh → Www*→ L±ΝL′±Ν′ +X In Pp̅ Collisions At √S = 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Oct 2006

Search For Associated Higgs Boson Production Wh → Www*→ L±ΝL′±Ν′ +X In Pp̅ Collisions At √S = 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We present a search for associated Higgs boson production in the process pp̅ → WH → WWW*→ l±νl′±ν′ +X in final states containing two like-sign isolated electrons or muons (ℯ±ℯ±, ℯ±μ±, or μ±μ±). The search is based on D0 run II data samples corresponding to integrated luminosities of 360–380 pb-1. No excess is observed over the predicted standard model background. We set 95% C.L. upper limits on σ(pp̅→WH) × (Br(H→ WW …

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High-Energy Product Exchange-Spring Fept/Fe Cluster Nanocomposite Permanent Magnets, X. Rui, Jeffrey E. Shield, Zhiguang Sun, Lanping Yue, Yinfan Xu, David J. Sellmyer, Z. Liu, D.J. Miller Oct 2006

High-Energy Product Exchange-Spring Fept/Fe Cluster Nanocomposite Permanent Magnets, X. Rui, Jeffrey E. Shield, Zhiguang Sun, Lanping Yue, Yinfan Xu, David J. Sellmyer, Z. Liu, D.J. Miller

David Sellmyer Publications

In this paper, we report on the production of Fe cluster/FePt matrix nanocomposite permanent magnets. Monodispersed Fe clusters with sizes below 10 nm were formed by gas aggregation techniques. These Fe clusters were imbedded in an FePt matrix by alternate deposition from two sources. Specimens with a range of Fe cluster phase content from 0 to 30 vol% were produced by controlling deposition times from each source. As-deposited FePt formed in the A1 structure; thus, post-deposition heat treatment was necessary to form the hard magnetic L10 FePt compound. A single-step heat treatment at 600 °C for 10 min leads …

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Atomic And Electronic Structure Of Cofeb/Mgo Interface From First Principles, John D. Burton, Sitaram S. Jaswal, Evgeny Y. Tsymbal, O. G. Heinonen Oct 2006

Atomic And Electronic Structure Of Cofeb/Mgo Interface From First Principles, John D. Burton, Sitaram S. Jaswal, Evgeny Y. Tsymbal, O. G. Heinonen

Evgeny Tsymbal Publications

First-principles calculations of the atomic and electronic structure of crystalline CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) are performed to understand the effect of B on spin-dependent transport in these junctions. The authors find that it is energetically favorable for B atoms to reside at the crystalline CoFeB/MgO interface rather than remain in the bulk of the crystalline CoFeB electrode. The presence of B at the interfaces is detrimental to tunneling magnetoresistance (TMR) because it significantly suppresses the majority-channel conductance through states of symmetry. Preventing B segregation to the interfaces during annealing should result in an enhanced TMR in CoFeB/MgO/CoFeB MTJs.

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A Continuum Model On The Nanomesa And Nanowell Formation In Langmuir-Blodgett Ferroelectric Polymeric Films, Jiang Yu Li, Yang Luo, Mengjun Bai, Stephen Ducharme Oct 2006

A Continuum Model On The Nanomesa And Nanowell Formation In Langmuir-Blodgett Ferroelectric Polymeric Films, Jiang Yu Li, Yang Luo, Mengjun Bai, Stephen Ducharme

Stephen Ducharme Publications

Spontaneous crystalline nanomesa and nanowell formation has recently been discovered in polyvinylidene fluoride trifluoroethylene [P(VDF– TrFE)] copolymer films developed by Langmuir–Blodgett (LB) deposition. In this paper, we propose a continuum field model to analyze this remarkable phenomenon, consisting of kinematics, energetics, and kinetics of pattern formation and evolution in P(VDF–TrFE) films. Linear perturbation analysis has been carried out to analyze the stability and growth of patterns under small perturbations, and finite difference numerical simulations have been implemented to simulate the morphologies and evolutions of nanomesas and nanowells. The effects of film thickness and a number of other material parameters have …

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Stephen Ducharme Publications 1983-2006 Sep 2006

Stephen Ducharme Publications 1983-2006

Stephen Ducharme Publications

Citations (and some links) for 68 articles in refereed journals, 1 book chapter, 5 conference proceedings edited, and 35 conference proceedings papers. Current through April 2006.

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Sy-Hwang Liou Publications 1982–2006 Sep 2006

Sy-Hwang Liou Publications 1982–2006

Sy-Hwang Liou Publications

Includes 204 articles and chapters, plus 2 patents. Current as of spring 2006.

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Search For Neutral Higgs Bosons Decaying To Tau Pairs In Pp̅ Collisions At √S = 1:96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Sep 2006

Search For Neutral Higgs Bosons Decaying To Tau Pairs In Pp̅ Collisions At √S = 1:96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

A search for the production of neutral Higgs bosons Φ decaying into τ+τ- final states in pp̅ collisions at a center-of-mass energy of 1.96 TeV is presented. The data, corresponding to an integrated luminosity of approximately 325 pb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. Since no excess compared to the expectation from standard model processes is found, limits on the production cross section times branching ratio are set. The results are combined with those obtained from the D0 search for Φb(b̅) →bb̅b( …

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Elliptic And Circular Dichroism Effects In Two-Photon Double Ionization Of Atoms, Andrei Y. Istomin, Evgeny Pronin, N. L. Manakov, S.I. Marmo, Anthony F. Starace Sep 2006

Elliptic And Circular Dichroism Effects In Two-Photon Double Ionization Of Atoms, Andrei Y. Istomin, Evgeny Pronin, N. L. Manakov, S.I. Marmo, Anthony F. Starace

Anthony F. Starace Publications

An ab initio parametrization of the two-photon double ionization amplitude from an s2 subshell of an atom in a 1S state is presented and used to predict two light polarization effects on photoelectron angular distributions that do not exist in single-photon double ionization: (i) elliptic dichroism and (ii) circular dichroism at equal energy sharing. Estimates for He show large magnitudes for these effects, which provide a means for polarization control of double ionization by vacuum ultraviolet light.

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In-Cluster-Structured Exchange-Coupled Magnets With High Energy Densities, X. Rui, Jeffrey E. Shield, Zhiguang Sun, Yinfan Xu, David J. Sellmyer Sep 2006

In-Cluster-Structured Exchange-Coupled Magnets With High Energy Densities, X. Rui, Jeffrey E. Shield, Zhiguang Sun, Yinfan Xu, David J. Sellmyer

David Sellmyer Publications

In this letter, the authors demonstrate isotropic Fe–Pt exchange-spring nanocomposite permanent magnets with a soft magnetic phase fraction of greater than 0.5 with a coercivity of 6.5 kOe, single-phase-like magnetic behavior, and an energy product of 25.1 MG Oe. Sub-10-nm Fe–Pt clusters are formed with compositions in the two-phase Fe3Pt and FePt regions. Intracluster structuring on a scale of a few nanometers occurs after appropriate heat treatment. This ensures full exchange coupling between the two phases, allowing greater soft magnetic phase fractions. The results provide insight into developing high energy product nanostructured permanent magnets.

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Search For Resonant Second Generation Slepton Production At The Fermilab Tevatron, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Sep 2006

Search For Resonant Second Generation Slepton Production At The Fermilab Tevatron, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We present a search for supersymmetry in the R-parity violating resonant production and decay of smuons and muon sneutrinos in the channels μ̃→ χ̃10μ, μ̃→ χ̃2,3,40μ, and ν̃μ→ χ̃1,2±μ. We analyzed 0:38 fb-1 of integrated luminosity collected between April 2002 and August 2004 with the D0 detector at the Fermilab Tevatron Collider. The observed number of events is in agreement with the standard model expectation, and we calculate 95% C.L. limits on the slepton production cross section times branching fraction to gaugino plus muon, as a function …

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Publisher’S Note: Limits On Anomalous Trilinear Gauge Couplings From Ww → ℯ+ ℯ-, Ww → ℯ±Μ±, And Ww → Μ+Μ- Events From Pp̅ Collisions At √S = 1.96 Tev [Phys. Rev. D 74, 057101 (2006)], V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Sep 2006

Publisher’S Note: Limits On Anomalous Trilinear Gauge Couplings From Ww → ℯ+ ℯ-, Ww → ℯ±Μ±, And Ww → Μ+Μ- Events From Pp̅ Collisions At √S = 1.96 Tev [Phys. Rev. D 74, 057101 (2006)], V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

This paper was published online on 8 September 2006 with a typographical error in the title. The title should read as ‘‘Limits on anomalous trilinear gauge couplings from WW → ℯ+ ℯ-, WW → ℯ±μ±, and WW → μ+μ- events from pp̅ collisions at √s =1:96 TeV’’. The title has been corrected as of 14 September 2006. The title is correct in the printed version of the journal.

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Limits On Anomalous Trilinear Gauge Couplings From Ww → E+E-, Ww → E± Μ±, And Ww → Μ+ Μ- Events From Pp̅ Collisions At √S =1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Sep 2006

Limits On Anomalous Trilinear Gauge Couplings From Ww → E+E-, Ww → E± Μ±, And Ww → Μ+ Μ- Events From Pp̅ Collisions At √S =1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

Limits are set on anomalous WWγ and WWZ trilinear gauge couplings using W+W- →e+vee-v̅e, W+W- →e±ve μ±v μ, and W+W- → μ+v μ μ-v̅ μ events. The data set was collected by the Run II D0 detector at the Fermilab Tevatron Collider and corresponds to approximately 250 pb-1 of integrated luminosity at √s = 1.96 TeV. Under the assumption that the WWγ couplings are equal to the WWZ …

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A Hand-Held Neutron Detection Sensor Systems, K. Osberg, N. Schemm, S. Balkir, Jennifer I. Brand, M. Susan Hallbeck, Peter A. Dowben Sep 2006

A Hand-Held Neutron Detection Sensor Systems, K. Osberg, N. Schemm, S. Balkir, Jennifer I. Brand, M. Susan Hallbeck, Peter A. Dowben

Peter Dowben Publications

In this paper, a hand-held neutron radiation sensor application is described. The sensor system utilizes a new class of boron-carbide diode that interacts with incoming neutrons. To interface with the boron-carbide diode an integrated front-end is designed in a 1.5/spl mu/m standard CMOS technology. With the diode and front-end microchip, a hand-held neutron detection system was realized with an embedded microcontroller for realtime processing. The hand-held detector operation was then tested with a plutonium-beryllium neutron source. Testing results confirm the validity of the approach and the functionality of the design.

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Nonextensivity In Magnetic Nanoparticle Ensembles, Christian Binek, Srinivas Polisetty, Xi He, Tathagata Mukherjee, Rajasekaran Rajesh, Jody G. Redepenning Sep 2006

Nonextensivity In Magnetic Nanoparticle Ensembles, Christian Binek, Srinivas Polisetty, Xi He, Tathagata Mukherjee, Rajasekaran Rajesh, Jody G. Redepenning

Department of Physics and Astronomy: Faculty Publications

A superconducting quantum interference device and Faraday rotation technique are used to study dipolar interacting nanoparticles embedded in a polystyrene matrix. Magnetization isotherms are measured for three cylindrically shaped samples of constant diameter but various heights. Detailed analysis of the isotherms supports Tsallis' conjecture of a magnetic equation of state that involves temperature and magnetic field variables scaled by the logarithm of the number of magnetic nanoparticles. This unusual scaling of thermodynamic variables, which are conventionally considered to be intensive, originates from the nonextensivity of the Gibbs free energy in three-dimensional dipolar interacting particle ensembles. Our experimental evidence for nonextensivity …

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Entanglement Evolution In The Presence Of Decoherence, Jin Wang, Herman Batelaan, Jeremy Podany, Anthony F. Starace Sep 2006

Entanglement Evolution In The Presence Of Decoherence, Jin Wang, Herman Batelaan, Jeremy Podany, Anthony F. Starace

Anthony F. Starace Publications

The entanglement of two qubits, each defined as an effective two-level, spin 1/2 system, is investigated for the case that the qubits interact via a Heisenberg XY interaction and are subject to decoherence due to population relaxation and thermal effects. For zero temperature, the time dependent concurrence is studied analytically and numerically for some typical initial states, including a separable (unentangled) initial state. An analytical formula for non-zero steady state concurrence is found for any initial state, and optimal parameter values for maximizing steady state concurrence are given. The steady state concurrence is found analytically to remain non-zero for low, …

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Interlayer Exchange Coupling In Fe/Mgo/Fe Magnetic Tunnel Junctions, T. Katayama, S. Yuasa, Julian P. Velev, M. Ye. Zhuravlev, Sitaram S. Jaswal, Evgeny Y. Tsymbal Sep 2006

Interlayer Exchange Coupling In Fe/Mgo/Fe Magnetic Tunnel Junctions, T. Katayama, S. Yuasa, Julian P. Velev, M. Ye. Zhuravlev, Sitaram S. Jaswal, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

Interlayer exchange coupling (IEC) in fully epitaxial Fe/MgO/Fe (001) tunnel junctions with wedge-shaped MgO layers is measured at room temperature from the unidirectional shift of the Kerr hysteresis loop. It is found that the IEC is antiferromagnetic for small MgO thickness but changes sign at 0.8 nm. Ab initio calculations of IEC show that this behavior can be explained by the presence of O vacancies in the MgO barrier which makes IEC antiferromagnetic for thin barriers. With increasing MgO thickness the resonance contribution to IEC from localized defect states is reduced resulting in the ferromagnetic coupling typical for perfect MgO …

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Numerical Computations In Us Undergraduate Physics Courses, Robert Fuller Sep 2006

Numerical Computations In Us Undergraduate Physics Courses, Robert Fuller

Robert G. Fuller Publications

A recent study conducted via email and Web surveys gathered responses from physics faculty members across the US about their use of numerical computations in the classroom. Responses showed a strong commitment to computational activities from some physics faculty and a frustration over the lack of such activities from others.

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An Investigation Of Electron Helicity Density In Bromocamphor And Dibromocamphor As A Source Of Electron Circular Dichroism, A.M. Scheer, Gordon A. Gallup, Timothy J. Gay Sep 2006

An Investigation Of Electron Helicity Density In Bromocamphor And Dibromocamphor As A Source Of Electron Circular Dichroism, A.M. Scheer, Gordon A. Gallup, Timothy J. Gay

Gordon Gallup Publications

We investigate the causes of electron-circular dichroism (ECD) in bromocamphor and dibromocamphor, focusing specifically on the electron helicity density of the target. Using electron transmission spectroscopy (ETS) and quantum chemical calculations, we have observed and assigned temporary negative ion states of bromocamphor and dibromocamphor. Further calculations were conducted to determine the helicity densities of these compounds. Large helicity densities are found in the regions of large wave function amplitude of the normally unoccupied molecular orbitals responsible for resonances in the scattering cross sections. We relate our ETS assignments and helicity density results to the chiral asymmetry data observed in electron-circular …

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Holographic Capture Of Femtosecond Pulse Propagation, Martin Centurion, Ye Pu, Demetri Psaltis Sep 2006

Holographic Capture Of Femtosecond Pulse Propagation, Martin Centurion, Ye Pu, Demetri Psaltis

Martin Centurion Publications

We have implemented a holographic system to study the propagation of femtosecond laser pulses with high temporal (150 fs) and spatial resolutions (4 μm). The phase information in the holograms allows us to reconstruct both positive and negative index changes due to the Kerr nonlinearity (positive) and plasma formation (negative), and to reconstruct three-dimensional structure. Dramatic differences were observed in the interaction of focused femtosecond pulses with air, water, and carbon disulfide. The air becomes ionized in the focal region, while in water long plasma filaments appear before the light reaches a tight focus. In contrast, in carbon disulfide the …

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Direct Synthesis Of Single-Walled Carbon Nanotubes Bridging Metal Electrodes By Laser-Assisted Chemical Vapor Deposition, J. Shi, Yongfeng Lu, K.J. Yi, Yushun Lin, Sy_Hwang Liou, J.B. Hou, X.W. Wang Aug 2006

Direct Synthesis Of Single-Walled Carbon Nanotubes Bridging Metal Electrodes By Laser-Assisted Chemical Vapor Deposition, J. Shi, Yongfeng Lu, K.J. Yi, Yushun Lin, Sy_Hwang Liou, J.B. Hou, X.W. Wang

Sy-Hwang Liou Publications

Direct synthesis of single-walled carbon nanotubes (SWNTs) bridging prepatterned Mo electrodes has been achieved using laser-assisted chemical vapor deposition (LCVD). The synthesized SWNTs are found predominantly semiconducting. By controlling the spot size of the focused laser beam, synthesis of SWNTs can be achieved in a localized manner, which is governed by the thermal and optical properties of materials as well as the laser parameters. The synthesis process is fast and can be achieved in both far- and near-infrared laser wavelength regions. LCVD method provides a potential approach to in situ remove SWNTs with specific chiralities during the growth. © 2006 …

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Origin Of The Interlayer Exchange Coupling In [Co/Pt]/Nio/ [Co/Pt] Multilayers Studied With Xas, Xmcd, And Micromagnetic Modeling, Andrew Baruth, D.J. Keavney, John D. Burton, Karolina Janicka, Evgeny Y. Tsymbal, Lu Yuan, Sy_Hwang Liou, Shireen Adenwalla Aug 2006

Origin Of The Interlayer Exchange Coupling In [Co/Pt]/Nio/ [Co/Pt] Multilayers Studied With Xas, Xmcd, And Micromagnetic Modeling, Andrew Baruth, D.J. Keavney, John D. Burton, Karolina Janicka, Evgeny Y. Tsymbal, Lu Yuan, Sy_Hwang Liou, Shireen Adenwalla

Sy-Hwang Liou Publications

The origin of the oscillatory interlayer exchange coupling in [Co/Pt] /NiO/ [Co/Pt] multilayers is investigated using advanced microscopy and spectroscopy techniques and micromagnetic modeling. X-ray magnetic circular dichroism (XMCD) measurements show the presence of the canting of Ni spins in the NiO film being greater for antiferromagnetically coupled multilayers than for ferromagnetically coupled ones. This behavior is consistent with the model, which assumes a different sign of the exchange coupling at the two interfaces and the antiferromagnetic layer-by-layer coupling in the NiO film. An unexpectedly short attenuation length of 4 Å for secondary electrons in NiO is measured, which has …

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Search For The Rare Decay BS0 → Φμ+ Μ- With The D0 Detector, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Aug 2006

Search For The Rare Decay BS0 → Φμ+ Μ- With The D0 Detector, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We present a search for the flavor-changing neutral current decay Bs0 → φμ+μ- using about 0.45 fb-1 of data collected in pp̅ collisions at √s = 1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. We find an upper limit on the branching ratio of this decay normalized to Bs0 → J/ ψφ of [Ɓ(Bs0 → φμ+μ-)] ÷ [Ɓ(Bs0 →J/ ψφ )]< 4.4 × 10-3 at the 95% C.L. Using the central value of the world average branching fraction …

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Publications David J. Sellmyer (Department Of Physics And Astronomy And Director Nebraska Center For Materials And Nanoscience - Ncmn), David J. Sellmyer Aug 2006

Publications David J. Sellmyer (Department Of Physics And Astronomy And Director Nebraska Center For Materials And Nanoscience - Ncmn), David J. Sellmyer

Department of Physics and Astronomy: Faculty Publications

Chronological list of 396 research articles and 45 books, chapters, and reviews. Covers the years 1995 through 2006 (August).

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Ferromagnetic Properties Of Epitaxial Manganite Films On Srtio3/Si Heterostructures, Aswini K. Pradhan, J.B. Dadson, D. Hunter, K. Zhang, S. Mohanty, E.M. Jackson, B. Lasley-Hunter, K. Lord, T.M. Williams, Rakhim R. Rakhimov, Jun Zhang, David J. Sellmyer, K. Inaba, T. Hasewaga, S. Mathews, B. Joseph, B.R. Sekhar, U.N. Roy, Y. Cui, A. Burger Aug 2006

Ferromagnetic Properties Of Epitaxial Manganite Films On Srtio3/Si Heterostructures, Aswini K. Pradhan, J.B. Dadson, D. Hunter, K. Zhang, S. Mohanty, E.M. Jackson, B. Lasley-Hunter, K. Lord, T.M. Williams, Rakhim R. Rakhimov, Jun Zhang, David J. Sellmyer, K. Inaba, T. Hasewaga, S. Mathews, B. Joseph, B.R. Sekhar, U.N. Roy, Y. Cui, A. Burger

David Sellmyer Publications

We report on the magnetic properties of epitaxial La0.7Ba0.3MnO3 and La0.7Sr0.3MnO3 films on Si (100) and Si (111) substrates using SrTiO3 template layer, which demonstrate magnetic and electrical properties at and above room temperature. The magnetization data show magnetic transition and magnetic hysteresis at and above room temperature. The films show well-defined magnetic domains. The ferromagnetic resonance studies show anisotropic effects related to ferromagnetic properties of films. The smaller grain size of about 20 nm in manganite films on SrTiO3 /Si may be one of the reasons to …

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Photodetachment Of H- By A Short Laser Pulse In Crossed Static Electric And Magnetic Fields, Liang-You Peng, Qiaoling Wang, Anthony F. Starace Aug 2006

Photodetachment Of H- By A Short Laser Pulse In Crossed Static Electric And Magnetic Fields, Liang-You Peng, Qiaoling Wang, Anthony F. Starace

Anthony F. Starace Publications

We present a detailed quantum mechanical treatment of the photodetachment of H- by a short laser pulse in the presence of crossed static electric and magnetic fields. An exact analytic formula is presented for the final state electron wave function (describing an electron in both static electric and magnetic fields and a short laser pulse of arbitrary intensity). In the limit of a weak laser pulse, final state electron wave packet motion is examined and related to the closed classical electron orbits in crossed static fields predicted by Peters and Delos [Phys. Rev. A 47, 3020 (1993)]. Owing to …

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Study Of Magnetic Layers In Magnetic Sensors, Lu Yuan Aug 2006

Study Of Magnetic Layers In Magnetic Sensors, Lu Yuan

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

Interest in highly sensitive magnetic sensors has been great due to their wide applications ranging from data storage to geomagnetic exploration. To achieve better performance, magnetic sensors are usually fabricated with micrometer-sized or submicrometer-sized multilayer structures. The thickness of each layer can be as thin as a few angstroms. The magnetic properties of these small and thin layers are quite different from those of the bulk. As the size of the magnetic devices shrinks and the thickness of the ferromagnetic films decreases, the chance of having defects becomes higher. Those defects may be formed during thin film deposition, annealing and …

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Assembly Of High-Anisotropy L10 Fept Nanocomposite Films, David J. Sellmyer, Yinfan Xu, M. L. Yan, Yucheng Sui, Jian Zhou, Ralph Skomski Aug 2006

Assembly Of High-Anisotropy L10 Fept Nanocomposite Films, David J. Sellmyer, Yinfan Xu, M. L. Yan, Yucheng Sui, Jian Zhou, Ralph Skomski

David Sellmyer Publications

In this paper we report results on the synthesis and magnetic properties of L10 FePt nanocomposite films. Three fabrication methods have been developed to produce high-anisotropy FePt films: non-epitaxial growth of (0 0 1)-oriented FePt:X (X=Ag, C) composite films that might be used for perpendicular media; monodispersed FePt(CFx) core–shell nanocluster-assembled films grown with a gas-aggregation technique and having uniform cluster size and narrow size distribution; and template-mediated self-assembled FePt clusters prepared with chemical synthesis by a hydrogen reduction technique, which has a high potential for controlling both cluster size and orientation. The magnetic properties are controllable through …

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Total Dissociative Electron Attachment Cross Sections For Molecular Constituents Of Dna, Kayvan Aflatooni, A.M. Scheer, Paul Burrow Aug 2006

Total Dissociative Electron Attachment Cross Sections For Molecular Constituents Of Dna, Kayvan Aflatooni, A.M. Scheer, Paul Burrow

Paul Burrow Publications

Total cross sections for the dissociative electron attachment process are presented for the DNA bases thymine, cytosine, and adenine and for three compounds used as surrogates for the ribose and phosphate groups, tetrahydrofuran, 3-hydroxytetrahydrofuran, and trimethylphosphate, respectively. Cross section magnitudes are obtained by observation of positive ion production and normalization to ionization cross sections calculated elsewhere using the binary-encounter-Bethe method. The average cross section of the three bases is 3–10 times smaller than the effective cross section per nucleotide reported for single strand breaks in surface-bound super-coiled DNA. Consequently, damage to the bases alone does not appear to account for …

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