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Iowa State University

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2003

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Full-Text Articles in Physics

Midrapidity Neutral-Pion Production In Proton-Proton Collisions At Root S 200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Dec 2003

Midrapidity Neutral-Pion Production In Proton-Proton Collisions At Root S 200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

The invariant differential cross section for inclusive neutral-pion production in p+p collisions at root s=200 GeV has been measured at midrapidity (\eta\<0.35) over the range 1 < p(T) less than or similar to 14 GeV/c by the PHENIX experiment at the Relativistic Heavy Ion Collider. Predictions of next-to-leading order perturbative QCD calculations are consistent with these measurements. The precision of our result is sufficient to differentiate between prevailing gluon-to-pion fragmentation functions.


Elliptic Flow Of Identified Hadrons In Au+Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Oct 2003

Elliptic Flow Of Identified Hadrons In Au+Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

The anisotropy parameter (v(2)), the second harmonic of the azimuthal particle distribution, has been measured with the PHENIX detector in Au+Au collisions at roots(NN)=200 GeV for identified and inclusive charged particle production at central rapidities (\eta\<0.35) with respect to the reaction plane defined at high rapidities (\eta\=3-4 ). We observe that the v(2) of mesons falls below that of (anti)baryons for p(T)>2 GeV/c, in marked contrast to the predictions of a hydrodynamical model. A quark-coalescence model is also investigated.


Scaling Properties Of Proton And Antiproton Production In Root S(Nn)=200 Gev Au+Au Collisions, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Oct 2003

Scaling Properties Of Proton And Antiproton Production In Root S(Nn)=200 Gev Au+Au Collisions, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

We report on the yield of protons and antiprotons, as a function of centrality and transverse momentum, in Au+Au collisions at rootS(NN)=200 GeV measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider. In central collisions at intermediate transverse momenta (1.5 < p(T) < 4.5 GeV/c) a significant fraction of all produced particles are protons and antiprotons. They show a centrality-scaling behavior different from that of pions. The (p) over bar/pi and p/pi ratios are enhanced compared to peripheral Au+Au, p+p, and e(+)e(-) collisions. This enhancement is limited to p(T) < 5 GeV/c as deduced from the ratio of charged hadrons to pi(0) measured in the range 1.5 < p (T) < 9 GeV/c.


Absence Of Suppression In Particle Production At Large Transverse Momentum In Root S(Nn)=200 Gev D+Au Collisions, S. S. Adler, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, F. K. Wohn, X. Zong, Et Al., Phenix Collaboration Aug 2003

Absence Of Suppression In Particle Production At Large Transverse Momentum In Root S(Nn)=200 Gev D+Au Collisions, S. S. Adler, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, F. K. Wohn, X. Zong, Et Al., Phenix Collaboration

Physics and Astronomy Publications

Transverse momentum spectra of charged hadrons with p(T)<8 GeV/c and neutral pions with p(T)<10 GeV/c have been measured at midrapidity by the PHENIX experiment at BNL RHIC in d+Au collisions at roots(NN)=200 GeV. The measured yields are compared to those in p+p collisions at the same roots(NN) scaled up by the number of underlying nucleon-nucleon collisions in d+Au. The yield ratio does not show the suppression observed in central Au+Au collisions at RHIC. Instead, there is a small enhancement in the yield of high momentum particles.


Suppressed Pi(0) Production At Large Transverse Momentum In Central Au Plus Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Aug 2003

Suppressed Pi(0) Production At Large Transverse Momentum In Central Au Plus Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

Transverse momentum spectra of neutral pions in the range 1 < p(T) < 10 GeV/c have been measured at midrapidity by the PHENIX experiment at BNL RHIC in Au+Au collisions at roots(NN)=200 GeV. The pi(0) multiplicity in central reactions is significantly below the yields measured at the same roots(NN) in peripheral Au+Au and p+p reactions scaled by the number of nucleon-nucleon collisions. For the most central bin, the suppression factor is similar to 2.5 at p(T)=2 GeV/c and increases to similar to 4-5 at p(T) approximate to 4 GeV/c. At larger p(T), the suppression remains constant within errors. The deficit is already apparent in semiperipheral reactions and increases smoothly with centrality.


Highly Directional Receiver And Source Antennas Using Photonic Band Gap Crystals, Rana Biswas, Gary L. Tuttle, Ekmel Ozbay, Burak Temelkuran, Mihail Sigalas, Kai-Ming Ho Jul 2003

Highly Directional Receiver And Source Antennas Using Photonic Band Gap Crystals, Rana Biswas, Gary L. Tuttle, Ekmel Ozbay, Burak Temelkuran, Mihail Sigalas, Kai-Ming Ho

Iowa State University Patents

A directional antenna made with photonic band gap structures has been presented. The directional antenna is formed with two photonic band gap structures oriented back to back and separated from each other by a distance to form a resonant cavity between the photonic band gap structures. An antenna element is placed in the resonant cavity. The resonant frequency of the cavity is tuned by adjusting the distance between the photonic band gap structures. The resonant cavity can be asymmetrical or symmetrical.


Method Of Making Active Magnetic Refrigerant, Colossal Magnetostriction And Giant Magnetoresistive Materials Based On Gd-Si-Ge Alloys, Karl A. Gschneidner Jr., Alexandra O. Pecharsky, Vitalij K. Pecharsky Jul 2003

Method Of Making Active Magnetic Refrigerant, Colossal Magnetostriction And Giant Magnetoresistive Materials Based On Gd-Si-Ge Alloys, Karl A. Gschneidner Jr., Alexandra O. Pecharsky, Vitalij K. Pecharsky

Iowa State University Patents

Method of making an active magnetic refrigerant represented by Gd5(SixGe1−x)4alloy for 0≦x≦1.0 comprising placing amounts of the commercially pure Gd, Si,and Ge charge components in a crucible, heating the charge contents under subambient pressure to a melting temperature of the alloy for a time sufficient to homogenize the alloy and oxidize carbon with oxygen present in the Gd charge component to reduce carbon, rapidly solidifying the alloy in the crucible, and heat treating the solidified alloy at a temperature below the melting temperature for a time effective to ...


A New Spectrometer Using Multiple Gratings With A Two-Dimensional Charge-Coupled Diode Array Detector, Tao Han, Wei-Ming Ni, Peng Zhao, Hai-Yang You, Jian-Hu Jia, Song-You Wang, Liang-Yao Chen, David W. Lynch Jun 2003

A New Spectrometer Using Multiple Gratings With A Two-Dimensional Charge-Coupled Diode Array Detector, Tao Han, Wei-Ming Ni, Peng Zhao, Hai-Yang You, Jian-Hu Jia, Song-You Wang, Liang-Yao Chen, David W. Lynch

Physics and Astronomy Publications

A new spectrometer with no moving parts uses a two-dimensional Si-based charge-coupled diode (CCD) array detector and an integrated grating consisting of three subgratings. The effective spectral range imaged on the detector is magnified threefold. The digitized spectral image in the 200–1000 nm wavelength range can be measured quickly. The nonlinear relationship between CCD pixel position and wavelength is corrected with multiple polynomial functions in the calibration procedure, which fits the data using a mathematical pattern-analysis method. The instrument can be applied for rapid spectroscopicdata analyses in many types of photoelectronic experiments and routine testing.


Centrality Dependence Of The High (Pt) Charged Hadron Suppression In Au+Au Collisions At Root S(Nn)=130 Gev, K. Adcox, Sergey Belikov, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Athanasios Petridis, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration May 2003

Centrality Dependence Of The High (Pt) Charged Hadron Suppression In Au+Au Collisions At Root S(Nn)=130 Gev, K. Adcox, Sergey Belikov, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Athanasios Petridis, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

PHENIX has measured the centrality dependence of charged hadron p(T) spectra from Au + Au collisions at root(s)NN = 130 GeV The truncated mean p(T) decreases with centrality for p(T) > 2 GeV/c, indicating an apparent reduction of the contribution from hard scattering to high p(T) hadron production. For central collisions the yield at high p(T) is shown to be suppressed compared to binary nucleon-nucleon collision scaling of p + p, data. This suppression is monotonically increasing with centrality, but most of the change occurs below 30% centrality, i.e., for collisions with less than similar ...


Magnetism, Elasticity, And Magnetostriction Of Fecoga Alloys, Liyang Dai, James Cullen, Manfred Wuttig, Thomas A. Lograsso, Eckhard Quandt May 2003

Magnetism, Elasticity, And Magnetostriction Of Fecoga Alloys, Liyang Dai, James Cullen, Manfred Wuttig, Thomas A. Lograsso, Eckhard Quandt

Ames Laboratory Publications

It is known that the substitution of Co for Fe gives rise to increases in magnetization and Curie temperature, not only in the bcc metals, but also in intermetallic compounds and alloys as well. With the expectation that this is the case in Co-substituted FeGa, we measured magnetization, Curie temperature, magnetostriction and elastic constants of a series of polycrystalline FeCoGa ternary alloys with up to 17% Ga and up to 10% Co. The magnetostriction at saturation for Fe0.93−xCo.07Gax increases to 90 ppm for x=0.17. For larger percentages of Co, the rise ...


Design Of High-Magnetic Field Gradient Sources For Controlling Magnetically Induced Flow Of Ferrofluids In Microfluidic Systems, W. He, S. J. Lee, David C. Jiles, D. H. Schmidt, Marc D. Porter, Ruth Shinar May 2003

Design Of High-Magnetic Field Gradient Sources For Controlling Magnetically Induced Flow Of Ferrofluids In Microfluidic Systems, W. He, S. J. Lee, David C. Jiles, D. H. Schmidt, Marc D. Porter, Ruth Shinar

Ames Laboratory Publications

The use of miniature electromagnets for ferrofluid-actuated liquid dispensing into microfluidic channels has been investigated by numerical simulations using the finite element method and measurements of fluid displacement and flow rate. The simulations illustrate the effect of structural and geometrical parameters of single and paired solenoid coils on the magnetic force experienced by the ferrofluid. Dual solenoids were used for extended fluid displacement. Ferrofluid positioning and flow rates were controlled also by using a solenoid with an iron core. The experimental measurements of fluidflow in capillaries were used to validate the modeling calculations. The results can be used as a ...


Microelectromagnetic Ferrofluid-Based Actuator, Y. Melikhov, S. J. Lee, David C. Jiles, D. H. Schmidt, Marc D. Porter, Ruth Shinar May 2003

Microelectromagnetic Ferrofluid-Based Actuator, Y. Melikhov, S. J. Lee, David C. Jiles, D. H. Schmidt, Marc D. Porter, Ruth Shinar

Ames Laboratory Publications

Computer simulations were used to investigate the performance of a microscale ferrofluid-based magnetic actuator developed for liquid dispensing in microfluidic channels. The actuation was based on the movement of a ferrofluid plug in a magnetic field gradient generated by on-chip effectively infinite parallel conductors. The movement, positioning, and retaining of ferrofluid plugs with different lengths at various locations along a microfluidic channel were investigated for two cases. In case (a), the magnetic field gradient was generated by a single conductor; when the ferrofluid reached its equilibrium position, the current was switched off and the nearest neighbor conductor was energized. A ...


Magnetic Field Induced Phase Transitions In Gd5(Si1.95ge2.05) Single Crystal And The Anisotropic Magnetocaloric Effect, H. Tang, A. O. Pecharsky, Deborah L. Schlagel, Thomas A. Lograsso, Vitalij K. Pecharsky, Karl A. Gschneidner Jr. May 2003

Magnetic Field Induced Phase Transitions In Gd5(Si1.95ge2.05) Single Crystal And The Anisotropic Magnetocaloric Effect, H. Tang, A. O. Pecharsky, Deborah L. Schlagel, Thomas A. Lograsso, Vitalij K. Pecharsky, Karl A. Gschneidner Jr.

Ames Laboratory Conference Papers, Posters, and Presentations

Magnetization measurements using a Gd5(Si1.95Ge2.05) single crystal with the magnetic field applied along three crystallographic directions, [001], [010] and [100], were carried out as a function of the applied field (0–56 kOe) at various temperatures (∼5–320 K). The magnetic field (H)–temperature (T) phase diagrams were constructed for theGd5(Si1.95Ge2.05) single crystal with field along the three directions. A small anisotropy was observed. The magnetocaloric effect was calculated from isothermal magnetization data, and the observed anisotropy correlates with the HT phase diagrams. The results ...


Extraordinary Magnetoelasticity And Lattice Softening In Bcc Fe-Ga Alloys, A. E. Clark, K. B. Hathaway, M. Wun-Fogle, J. B. Restorff, Thomas A. Lograsso, V. M. Keppens, G. Petculescu, R. A. Taylor May 2003

Extraordinary Magnetoelasticity And Lattice Softening In Bcc Fe-Ga Alloys, A. E. Clark, K. B. Hathaway, M. Wun-Fogle, J. B. Restorff, Thomas A. Lograsso, V. M. Keppens, G. Petculescu, R. A. Taylor

Ames Laboratory Conference Papers, Posters, and Presentations

Extraordinary magnetostrictive behavior has been observed in Fe-Ga alloys with concentrations of Ga between 4% and 27%. λ100 exhibits two peaks as a function of Ga content. At room temperature, λ100 reaches a maximum of 265 ppm near 19% Ga and 235 ppm near 27% Ga. For compositions between 19% and 27%, λ100 drops sharply to a minimum near 24% Ga and exhibits an anomalous temperature dependence, decreasing by as much as a factor of 2 at low temperatures. This unusual magnetostrictive behavior is interpreted on the basis of a single maximum in the magnetoelastic coupling ∣b ...


In Situ Applied Field Imaging Of A Magnetic Tunnel Junction Using Magnetic Force Microscopy, J. S. Leib, Chester C.H. Lo, John E. Snyder, David C. Jiles May 2003

In Situ Applied Field Imaging Of A Magnetic Tunnel Junction Using Magnetic Force Microscopy, J. S. Leib, Chester C.H. Lo, John E. Snyder, David C. Jiles

Materials Science and Engineering Publications

Knowledge of domain behavior in magnetic tunnel junctions is an essential component, together with knowledge of the electron band structure, for understanding their magnetoelectronic properties. To this purpose, the magnetization reversal processes of a multilayertunnel junction of structure substrate/NiFe/AlOx/FeCo/CrPtMn/Al of tapered half-ellipsoid shape have been imaged using a magnetic force microscope(MFM) within situ applied magnetic fields. Stripe domains through both the stack and free layers observed at zero applied field were erased by a ∼100 Oe field applied to the left followed by applying a small field to the right. Magnetic domain structure ...


Hexagonal And Square Flux Line Lattices In Cecoin5, Morten Ring Eskildsen, Charles D. Dewhurst, Bart W. Hoogenboom, Cedomir Petrovic, Paul C. Canfield May 2003

Hexagonal And Square Flux Line Lattices In Cecoin5, Morten Ring Eskildsen, Charles D. Dewhurst, Bart W. Hoogenboom, Cedomir Petrovic, Paul C. Canfield

Ames Laboratory Publications

Using small-angle neutron scattering, we have imaged the magnetic flux line lattice (FLL) in the d-wave heavy-fermion superconductor CeCoIn5. At low fields we find a hexagonal FLL. Around 0.6 T this undergoes what is most likely a first-order transition to square symmetry, with the nearest neighbors oriented along the gap node directions. This orientation of the square FLL is consistent with theoretical predictions based on the d-wave order parameter symmetry.


Phenix Detector Overview, K. Adcox, Sergey Belikov, S. Bhagavatula, Paul Constantin, K. C. Cook, John C. Hill, John G. Lajoie, Alexandre Lebedev, B. Libby, Craig Ogilvie, A. N. Petridis, T. Plagge, Marzia Rosati, Harold D. Skank, S. Skutnik, G. A. Sleege, W. D. Thomas, T. Weimer, F. K. Wohn, L. Wood, Et Al., Phenix Collaboration Mar 2003

Phenix Detector Overview, K. Adcox, Sergey Belikov, S. Bhagavatula, Paul Constantin, K. C. Cook, John C. Hill, John G. Lajoie, Alexandre Lebedev, B. Libby, Craig Ogilvie, A. N. Petridis, T. Plagge, Marzia Rosati, Harold D. Skank, S. Skutnik, G. A. Sleege, W. D. Thomas, T. Weimer, F. K. Wohn, L. Wood, Et Al., Phenix Collaboration

Physics and Astronomy Publications

The PHENIX detector is designed to perform a broad study of A–A, p–A, and p–p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed ...


Optical Properties And Electronic Structures Of Single Crystalline Ral3(R=Sc, Yb, And Lu), S. J. Lee, J. M. Park, Paul C. Canfield, David W. Lynch Feb 2003

Optical Properties And Electronic Structures Of Single Crystalline Ral3(R=Sc, Yb, And Lu), S. J. Lee, J. M. Park, Paul C. Canfield, David W. Lynch

Physics and Astronomy Publications

The optical conductivities of single crystals of ScAl3, LuAl3, and YbAl3 were measured by spectroscopic ellipsometry in the energy range of 1.5–5.5 eV. The conductivity spectra of all show peaks between 1.5 and 2.0 eV originating from interband transitions. Two additional peaks around at 2.9 and 4.2 eV are observed for ScAl3, and a weak shoulder is observed around at 2.8 eV for LuAl3. Band structure, density of states, and optical conductivity were calculated using the full-potential linear augmented plane wave method. The calculated conductivity spectrum for ScAl3 shows peaks around at ...


Rate Equation Theory For Island Sizes And Capture Zone Areas In Submonolayer Deposition: Realistic Treatment Of Spatial Aspects Of Nucleation, James W. Evans, Maozhi Li, M. C. Bartelt Jan 2003

Rate Equation Theory For Island Sizes And Capture Zone Areas In Submonolayer Deposition: Realistic Treatment Of Spatial Aspects Of Nucleation, James W. Evans, Maozhi Li, M. C. Bartelt

Physics and Astronomy Conference Papers, Posters and Presentations

Extensive information on the distribution of islands formed during submonolayer deposition is provided by the joint probability distribution (JPD) for island sizes, s, and capture zone areas, A. A key ingredient determining the form of the JPD is the impact of each nucleation event on existing capture zone areas. Combining a realistic characterization of such spatial aspects of nucleation with a factorization ansatz for the JPD, we provide a concise rate equation formulation for the variation with island size of both the capture zone area and the island density.


Decoupling Of The Magnetic And Structural Transformations In Er5si4, Vitalij K. Pecharsky, Alexandra O. Pecharsky, Yurij Mozharivskyj, Karl A. Gschneidner Jr., Gordon J. Miller Jan 2003

Decoupling Of The Magnetic And Structural Transformations In Er5si4, Vitalij K. Pecharsky, Alexandra O. Pecharsky, Yurij Mozharivskyj, Karl A. Gschneidner Jr., Gordon J. Miller

Chemistry Publications

Er5Si4 is a member of the R5(Si4−xGex) family of alloys, where R=rare earth metal. Many of these compounds display a strong coupling between the magnetic and crystal lattices. In the naturally layered R5(Si4−xGex) materials, inter- and intralayer interactions can be controlled by chemical and physical means; thus their physical properties can be tailored within wide limits. The Er5Si4 is unique in that the temperature dependent structural sequence is opposite that of other representatives of this family. The magnetism of Er5Si4 is reflective of its exceptional place within the series.


The Intermetallic Compound Gd6ta4al43, Cathie L. Condron, Joel D. Strand, Paul C. Canfield, Gordon J. Miller Jan 2003

The Intermetallic Compound Gd6ta4al43, Cathie L. Condron, Joel D. Strand, Paul C. Canfield, Gordon J. Miller

Chemistry Publications

The elements Gd (99.999%; Ames Laboratory), Ta (99.999%; Ames Laboratory), and Al (99.98%; Alfa) were combined in the atomic ratio Gd6Ta4Al100 in a 2 ml alumina crucible. The crucible was placed into a fused silica tube and a second crucible, filled with SiO2 wool, was placed inverted on top of the first. The tube was sealed under 1/5 atm Ar and placed into a box furnace. The mixture was heated to 1463 K in 3 h, kept at 1463 K for 2 h, and then cooled to 1173 K over ...


A New Look At Bonding In Trialuminides:  Reinvestigation Of Taal3, C.L. Condron, Gordon J. Miller, Joel D. Strand, Sergey L. Bud'ko, Paul C. Canfield Jan 2003

A New Look At Bonding In Trialuminides:  Reinvestigation Of Taal3, C.L. Condron, Gordon J. Miller, Joel D. Strand, Sergey L. Bud'ko, Paul C. Canfield

Chemistry Publications

Single crystals of TaAl3 were grown at high temperatures from an Al-rich, binary solution. TaAl3 adopts the D022 structure type, space group I4/mmm with a = 3.8412(5) Å, c = 8.5402(17) Å, and Z = 2. The structure type, which is the preferred structure for all group 5 trialuminides and TiAl3 as well as the high-temperature form of HfAl3, is a binary coloring of the face-centered-cubic (fcc) arrangement. The distribution of Ta atoms creates a three-dimensional network of vertex and edge-sharing square pyramids of Al atoms. Temperature-dependent electrical resistivity and magnetic susceptibility ...


Anisotropy And Large Magnetoresistance In The Narrow-Gap Semiconductor Fesb2, Cedomir Petrovic, J.W. Kim, Sergey L. Bud'ko, A. I. Goldman, Paul C. Canfield, Wonyoung Choe, Gordon J. Miller Jan 2003

Anisotropy And Large Magnetoresistance In The Narrow-Gap Semiconductor Fesb2, Cedomir Petrovic, J.W. Kim, Sergey L. Bud'ko, A. I. Goldman, Paul C. Canfield, Wonyoung Choe, Gordon J. Miller

Chemistry Publications

A study of the anisotropy in magnetic, transport, and magnetotransport properties of FeSb2 has been made on large single crystals grown from Sb flux. Magnetic susceptibility of FeSb2 shows diamagnetic to paramagnetic crossover around 100 K. Electrical transport along two axes is semiconducting, whereas the third axis exhibits a metal-semiconductor crossover at temperature Tcr which is sensitive to current alignment and ranges between 40 and 80 K. In H=70kOe semiconducting transport is restored for T<300K, resulting in large magnetoresistance [ρ(70kOe)−ρ(0)]/ρ(0)=2200% in the crossover temperature range.


Fabrication Of Photonic Band Gap Crystal Using Microtransfer Molded Templates, Wai Y. Leung, Henry Kang, Kristen P. Constant, D. Cann, Chang-Hwan Kim, Rana Biswas, M. M. Sigalas, Kai-Ming Ho Jan 2003

Fabrication Of Photonic Band Gap Crystal Using Microtransfer Molded Templates, Wai Y. Leung, Henry Kang, Kristen P. Constant, D. Cann, Chang-Hwan Kim, Rana Biswas, M. M. Sigalas, Kai-Ming Ho

Materials Science and Engineering Publications

We have proposed and demonstrated an economical technique to fabricate a three-dimensional layer-by-layer photonic band gapstructure in the infrared wavelengths. An organic polymer template structure, an inverse layer-by-layer photonic crystalstructure, is assembled using the microtransfer molding technique. This template is infiltrated with sol-gel or nanoparticle titanium oxide slurry, then later removed by heat treatment at a temperature range of 550–800 °C. This method can be extended to fabricatephotonic crystals operating at optical and ultraviolet frequencies.