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Published Date
Displaying 951 - 975 of 1261

Beyond s-wave scattering for ultracold atoms

January 20, 2012
Author(s)
Ross A. Williams, Lindsay J. LeBlanc, Karina K. Jimenez Garcia, Matthew C. Beeler, Abigail R. Perry, William D. Phillips, Ian B. Spielman
Interactions between particles can be strongly altered by their environment. Here we demonstrate a technique for modifying interactions between ultracold atoms by dressing the bare atomic states with light, creating a screened interaction of vastly

Spin-Charge-Density Wave in a Squircle-Like Fermi Surface for Ultracold Atoms

January 20, 2012
Author(s)
Ian B. Spielman, Dima Makogon, Christiane de Morais Smith
We derive and discuss an experimentally realistic model describing ultracold atoms in an optical lattice including a commensurate, but staggered, Zeeman field. The resulting band structure is quite exotic; fermions in the third band have an unusual rounded

Effect of elastic deformation on frictional properties of few-layer graphene

January 9, 2012
Author(s)
Alexander Y. Smolyanitsky, Jason P. Killgore, Vinod K. Tewary
We describe the results of Brownian dynamics (BD) simulations of an AFM tip scanned on locally suspended few-layer graphene. The effects of surface compliance and sample relaxation are directly related to the observed friction force. We demonstrate that

Chern Numbers Hiding in Time-of-Flight Images

December 21, 2011
Author(s)
Ian B. Spielman, Erhai Zhao, Noah Bray-Ali, Carl J. Williams, Indubala Satija
We present a novel technique for detecting topological invariants -- Chern numbers -- from time-of-flight images of ultra-cold neutral atoms. The Chern number of fermions in a lattice potential depends on magnetic field (for neutral atoms, generated by an

Correlation between in-plane grain orientation and the reversible strain effect on flux pinning in RE-Ba 2 Cu 3 O 7-d coated conductors

December 16, 2011
Author(s)
Daniel C. van der Laan, Loren F. Goodrich, Fraser Douglas, R. Semerad, M Bauer
The pressure dependence of the critical temperature causes a reversible effect of strain on the critical current density and flux pinning strength in many high-temperature superconductors. Recent experiments on patterned coated conductor bridges have shown

Correlation Between the Pressure Dependence of the Critical Temperature and the Reversible Strain Effect on the Critical Current and Pinning Force in Bi 2 Sr 2 CaCu 2 O 8+x Wires

December 16, 2011
Author(s)
Xifeng Lu, Loren F. Goodrich, Daniel C. van der Laan, Jolene D. Splett, Najib Cheggour, T G. Holesinger, F J. Baca
Bi 2Sr 2CaCu 2O 8+x round wires are among the most promising high-temperature superconductor candidates for making high-field magnets that operate at fields above 20 Tesla. Owing to the brittle nature of high-temperature superconductors, their electro

Insensitivity of Sub-Kelvin Electron-Phonon Coupling to Substrate Properties

December 16, 2011
Author(s)
Jason M. Underwood, Peter J. Lowell, Galen C. O'Neil, Joel N. Ullom
We have examined the role of the substrate on electron-phonon coupling in normal metal films of Mn-doped Al at temperatures below 1 K. Normal metal-insulator-superconductor junctions were used to measure the electron temperature in thin metal films as a

Quantum Hall effect on centimeter scale chemical vapor deposited graphene films

December 7, 2011
Author(s)
Tian T. Shen, Wei Wu, Qingkai Yu, Curt A. Richter, Randolph E. Elmquist, David B. Newell, Yong P. Chen
We report observations of well developed half integer quantum Hall effect on mono layer graphene films of 7 mm × 7 mm in size. The graphene films are grown by chemical vapor deposition on copper, then transferred to SiO2/Si substrates, with typical carrier

Reversible effect of strain on transport critical current in Bi 2 Sr 2 CaCu 2 O 8+x superconducting wires: A modified descriptive strain model

December 5, 2011
Author(s)
Najib Cheggour, Xifeng Lu, T G. Holesinger, Theodore C. Stauffer, J Jiang, Loren F. Goodrich
A reversible strain effect on transport critical current I c was found in Bi 2Sr 2CaCu 2O 8+x (Bi-2212) high-temperature superconducting round wires. I c showed unambiguous reversibility at 4 K and 16 T up to an irreversible strain limit of about 0.3 % in

Viewpoint: Topological Invariants Made Manifest

November 28, 2011
Author(s)
Ian B. Spielman, Gediminas Juzeliunas
Topological order in some single particle cold atom systems can now be measured directly, instead of relying on proxies such as the quantized Hall conductance as is usually the case in conventional materials. This new measurement technique complements the

Discovery of giant magnetostriction in annealed Co1-xFex thin-films

November 1, 2011
Author(s)
Dwight Hunter, William Alexander Osborn, Ke Wang, Nataliya Kazantseva, Jason Hattrick-Simpers, Richard Suchoski, Ryota Takahashi, Marcus L. Young, Apurva Mehta, Leonid A. Bendersky, Sam E. Lofland, Manfred Wuttig, Ichiro Takeuchi
Chemical and structural heterogeneity and resulting interaction of coexisting phases can lead to extraordinary behaviors in oxides as observed in piezoelectric materials at morphotropic phase boundaries and relaxor ferroelectrics. But such phenomena are

Anisotropic in-plane reversible strain effect in Y 0.5 Gd 0.5 Ba 2 Cu 3 O 7-d coated conductors

October 19, 2011
Author(s)
Daniel C. van der Laan, Dmytro Abraimov, A A. Polyanskii, David C. Larbalestier, J. F. Douglas, R. Semerad, M Bauer
Recent experiments have shown that reversible effects of strain on the critical current density and flux pinning strength in the high-temperature superconductor Bi 2Sr 2Ca 2Cu 3O x can be explained entirely by the pressure dependence of its critical

Magnetization textures in NiPd nanostructures

September 15, 2011
Author(s)
Jean-Yves Chauleau, Benjamin James McMorran, R. Belkhou, Nicolas Bergeard, Tevfik Mente?, Miguel Angel Nino, Andrea Locatelli, John Unguris, Stanislas Rohart, Jacques Miltat, Andre Thiaville
We have observed peculiar magnetization textures in Ni80Pd20 nanostructures, by three different imaging techniques (MFM, XMCD-PEEM and SEMPA). The appearance of diamond-like domains with strong lateral charges, and of weak stripes structures brings into

Graphene-metal interconnect: an atomistic simulation

August 11, 2011
Author(s)
Alexander Y. Smolyanitsky, Vinod K. Tewary
We develop a set of computationally efficient and accurate interatomic interactions for an atomistic simulation of the properties of graphene on nickel surface. The approach is based on the modified embedded atom method (MEAM) for the C-C and Ni-Ni

Controlling Formation of Atomic Step Morphology on Micro-patterned Si (100)

August 9, 2011
Author(s)
Kai Li, Pradeep Namboodiri, Sumanth B. Chikkamaranahalli, Gheorghe Stan, Ravikiran Attota, Joseph Fu, Richard M. Silver
Micro scale features are fabricated on Si (100) surfaces using lithographic techniques and then thermally processed in an ultra high vacuum (UHV) environment. Samples are flash heated at 1200 °C and further annealed at 1050 °C for 18 hours. The surface
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