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Physics

Condensed matter

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Displaying 726 - 750 of 1244

Epitaxial graphene homogeneity and quantum Hall effect in millimeter-scale devices

April 1, 2017
Author(s)
Yanfei Yang, Guangjun Cheng, Chiashain Chuang, Angela R. Hight Walker, Randolph E. Elmquist, Irene G. Calizo, Randall M. Feenstra, Patrick Mende
Quantized magnetotransport is observed in 5.6 × 5.6 mm2 epitaxial graphene devices, grown using highly constrained sublimation on the Si-face of SiC(0001) at high temperature (1900 °C). The precise quantized Hall resistance of Rxy = h/〖2e〗^2 is maintained

Reduced Bimolecular Recombination in Blade-Coated, High-Efficiency, Small-Molecule Solar Cells

March 22, 2017
Author(s)
Sebastian Engmann, Hyun W. Ro, Andrew A. Herzing, Dean M. DeLongchamp, Chad R. Snyder, Lee J. Richter, Adam J. Barito, David J. Gundlach
The full benefit of emerging solution deposited photovoltaic devices requires development of processes compatible with high speed manufacturing. Extensive studies of the lab-to-fab challenge have been performed on polymer donor based organic photovoltaics

Reference Correlation for the Viscosity of Carbon Dioxide

March 21, 2017
Author(s)
Arno D. Laesecke, Chris D. Muzny
A comprehensive database of experimental and computed data for the viscosity of carbon dioxide (CO2) was compiled and a new reference correlation was developed. Literature results based on an ab initio potential energy surface were the foundation of the

Chiral magnetoresistance in Pt/Co/Pt zigzag wires

March 20, 2017
Author(s)
Kyoung-Whan Kim, Yuxiang Yin, Dong-Soo Han, June-Seo Kim, Lavrijsen Reinoud, Kyung-Jin Lee, Seo--Won Lee, Hyun-Woo Lee, Henk Swagten, Bert Koopmans
The Rashba effect leads to a chiral rotation of conduction spins while the Dzyaloshinskii-Moriya interaction (DMI) fixes the chirality of the profile of local spins. We predict that these two spin systems interact with each other via s-d exchange, and

Electronic Structure of Single Crystal a-Perylene

March 16, 2017
Author(s)
Sujitra J. Pookpanratana, Katelyn Goetz, Ruslan Ovsyannikov, Erika Giangrisostomi, Emily G. Bittle, Oana Jurchescu, Steven W. Robey, Christina A. Hacker
In organic electronics, the highest estimated charge mobility in a device is typically achieved when the organic semiconductor is a single crystal. However, the measurement of the electronic and chemical structure of organic single crystals by

Spin Excitations and the Fermi Surface of Superconducting FeS

March 10, 2017
Author(s)
Haoran Man, Jiangang Guo, Rui Zhang, Rico U. Schonemann, Zhiping Yin, Mingxuan Fu, Matthew B. Stone, Qingzhen Huang, Yu Song, Weiyi Wang, David J. Singh, Felix Lochner, Tillman Hickel, Ilya Eremin, Leland Harriger, Jeffrey W. Lynn, Collin L. Broholm, Luis Balicas, Qimiao Si, Pengcheng Dai

Disordered Route to the Coulomb Quantum Spin Liquid: Random Transverse Fields on Spin Ice in Pr 2 Zr 2 O 7

March 8, 2017
Author(s)
J.-J. Wen, S.M. Koohpayeh, K. A. Ross, B. A. Trump, T. M. McQueen, K. Kimura, S. Nakatsuji, Yiming Qiu, D. M. Pajerowski, John R. Copley, Collin L. Broholm
Inelastic neutron scattering reveals a broad continuum of excitations in Pr 2Zr 2O 7, the temperature and magnetic field dependence of which indicate a continuous distribution of quenched transverse fields (Δ}) acting on the non-Kramers Pr 3+ crystal

High-resolution valence and core excitation spectra of solid C60 via first-principles calculations and experiment

March 8, 2017
Author(s)
Eric L. Shirley, Keith Gilmore, Josh J. Kas, John J. Rehr, Fernando D. Vila, Frederic Fossard, Gilles Hug
We present calculated optical and carbon 1s near-edge spectra of crystalline and molecular C60 and those measured with high-resolution electron energy-loss spectroscopy. The near-edge calculations are carried out using three different methods: solution of

Sodium Layer Chiral Distribution and Spin Structure of Na 2 Ni 2 TeO 6 with a Ni Honeycomb Lattice

March 8, 2017
Author(s)
Sunil K. Karna, Yang Zhao, R. Sankar, M. Avdeev, P. C. Tseng, C. W. Wang, G. J. Shu, K. Matan, G. Y. Guo, F. C. Chou
The crystal structure of P2-type Na 2Ni 2TeO 6 is best described as layers that are composed of Te-centered edge-sharing NiO 6 octahedra in honeycomb lattice with intercalated Na ions in the van der Waals (vdW) gaps. Although the crystal symmetry has been

Accurate X-Ray Spectral Predictions: An Advanced Self-Consistent-Field Approach Inspired by Many-Body Perturbation Theory

March 2, 2017
Author(s)
Yufeng Liang, John Vinson, Chaitanya D. Pemmaraju, Walter Drisdell, Eric L. Shirley, David Prendergast
The self-consistent-field method and the many-body approach are two cornerstones for obtaining electronic excitations from first- principles. Using the two distinct theories, we study the O 1s core excitations that have become increasingly important for

Observation of optomechanical buckling phase transitions

March 1, 2017
Author(s)
Jacob M. Taylor, John R. Lawall, Haitan Xu, Utku Kemiktarak, Jingyun Fan, Stephen Ragole
Correlated phases of matter provide long-term stability for systems as diverse as solids, magnets, and potential exotic quantum materials. Mechanical systems, such as relays and buckling transition spring switches can yield similar stability by exploiting

Predicting low-temperature free energy landscapes with flat-histogram Monte Carlo methods

February 21, 2017
Author(s)
Nathan Mahynski, Marco A. Blanco Medina, Jeffrey R. Errington, Vincent K. Shen
We present a method of predicting the free energy landscape of fluids at low temperatures from flat-histogram grand canonical Monte Carlo simulations performed at higher ones. We illustrate our approach for both pure and multicomponent systems using two

Ba 8 CoNb 6 O 24 : A Spin-1/2 Triangular-Lattice Heisenberg Antiferromagnet in the Two-Dimensional Limit

February 17, 2017
Author(s)
R. Rawl, L. Ge, H. Agrawal, Y. Kamiya, C. R. Dela Cruz, Nicholas Butch, X. F. Sun, M. Lee, E. S. Choi, J. Oitmaa, C. D. Batista, M. Mourigal, H. D. Zhou, J. Ma
The quasi-two-dimensional perovskite Ba 8CoNb 6O 24 comprises equilateral effective spin-1/2 Co 2+ triangular layers separated by six nonmagnetic Nb 5+ layers. Susceptibility, specific heat and neutron scattering measurements combined with high-temperature

Field Programmable Josephson Amplifier for non-reciprocal microwave signal processing

February 17, 2017
Author(s)
Florent Q. Lecocq, Leonardo Ranzani, Gabriel A. Peterson, Katarina Cicak, Raymond W. Simmonds, John D. Teufel, Jose A. Aumentado
We report on the design and implementation of a Field Programmable Josephson Amplifier (FPJA) - a compact and lossless superconducting circuit that can be programmed in-situ by a set of microwave drives to perform reciprocal and non-reciprocal frequency

Partial breakdown of quantum thermalization in a Hubbard-like model

February 17, 2017
Author(s)
James R. Garrison, Ryan Mishmash, Matthew P. Fisher
We study the possible breakdown of quantum thermalization in a model of itinerant electrons on a one-dimensional chain without disorder, with both spin and charge degrees of freedom. The eigenstates of this model exhibit peculiar properties in the

Ultrafast time-resolved x-ray absorption spectroscopy of ferrioxalate photolysis with a laser plasma x-ray source and microcalorimeter array

February 17, 2017
Author(s)
Galen C. O'Neil, Joel N. Ullom, Luis Miaja Avila, Young Il Joe, Joseph W. Fowler, Carl D. Reintsema, Daniel S. Swetz, Kevin L. Silverman, Daniel R. Schmidt, Bruce D. Ravel, Gene C. Hilton, William B. Doriese, Bradley K. Alpert, Ralph Jimenez
Using a table-top apparatus based upon a laser plasma x-ray source and an array of cryogenic microcalorimeter x-ray detectors, we have measured the transient x-ray absorption spectrum during the ferrioxalate photoreduction reaction. We observe the Fe K

Unified scaling law for flux pinning in practical superconductors: Part 3. Extrapolations from minimum datasets and applications of the extrapolative scaling expression

February 16, 2017
Author(s)
John (Jack) W. Ekin, Najib Cheggour, Loren F. Goodrich, Jolene D. Splett
The accuracy of present fitting equations to interpolate and extrapolate full Ic(B,T,ε) datasets is evaluated and compared with the extrapolative scaling expression (ESE) derived in Part 2. Accuracy is analyzed in terms of RMS error and fractional

Enabling photoemission electron microscopy in liquids via graphene-capped microchannel arrays

February 8, 2017
Author(s)
Hongxuan Guo, Evgheni Strelcov, Alexander Yulaev, Jian Wang, Narayana Appathurai, Stephen Urquhart, John Vinson, Subin Sahu, Michael P. Zwolak, Andrei Kolmakov
Photoelectron emission microscopy (PEEM) is a powerful tool to spectroscopically access dynamic surface processes at the nanoscale but is traditionally limited to ultra-high or moderate vacuum conditions. Here, we develop a novel graphene-capped

Ultrafast modulation of x-ray absorption by coherent phonon excitations

February 1, 2017
Author(s)
Eric L. Shirley, Jannick Weisshaupt, Michael Woerner, Marc J. Vrakking, Thomas Elsaesser, Andreas Borgschulte
X-ray absorption in solids promotes an electron from an atomic core level to the conduction band states, and near-edge spectra structure gives insight into local atomic geometry and chemical bonding effects. Based on a novel implementation of femtosecond x
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