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Physics

Condensed matter

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Displaying 726 - 750 of 1261

Gapped Excitations in the High-Pressure Antiferromagnetic Phase of URu 2 Si 2

May 31, 2017
Author(s)
T. J. Williams, H. Barath, Z. Yamani, Jose Rodriguez Rivera, Juscelino Leao, J. D. Garrett, G. M. Luke, W.J. L. Buyers, Collin L. Broholm
We report a neutron scattering study of the magnetic excitation spectrum in each of the three temperature and pressure phases of URu 2Si 2. We find qualitatively similar excitations throughout the (H0L)scattering plane in the hidden order and large moment

Phase Diagram of a-RuCl 3 in an In-Plane Magnetic Field

May 31, 2017
Author(s)
J. A. Sears, Yang Zhao, Zhijun Xu, Jeffrey W. Lynn, Young-June Kim
The low-temperature magnetic phases in the layered honeycomb lattice material α-RuCl 3 have been studied as a function of in-plane magnetic field. In zero field this material orders magnetically below 7 K with so-called zigzag order within the honeycomb

Temperature and Radiation Effects at the Fluorine K-edge in LiF

May 30, 2017
Author(s)
Craig P. Schwartz, Francisco Ponce, Stephan Friedrich, Stephen P. Cramer, John Vinson, David Prendergast
The F K-edge of LiF is studied both experimentally and theoretically as a function of temperature. Instantaneous thermal fluctuations in atomic positions are shown in molecular dynamics simulations to increase in amplitude from 0.029 - 0.064 Å in the

Overlap junctions for high coherence superconducting qubits

May 26, 2017
Author(s)
Xian Wu, Junling Long, Hsiang S. Ku, Russell Lake, Mustafa Bal, David P. Pappas
Fabrication of sub-micron Josephson junctions is demonstrated using standard processing techniques for high-coherence, superconducting qubits. These junctions are made in two separate lithography steps with normal-angle evaporation. Most significantly

Electrical stabilization of surface resistivity in epitaxial graphene systems by amorphous boron nitride encapsulation

May 25, 2017
Author(s)
Albert F. Rigosi, Chieh-I Liu, Nicholas R. Glavin, Yanfei Yang, Heather M. Hill, Jiuning Hu, Angela R. Hight Walker, Curt A. Richter, Randolph E. Elmquist, David B. Newell
Homogeneous monolayer epitaxial graphene (EG) is an ideal candidate for the development of millimeter-sized devices with single-crystal domains. A clean fabrication process was used to produce EG-based devices with n-type doping level of order 10^12 cm^-2

Counting Near Infrared Photons with Microwave Kinetic Inductance Detectors

May 22, 2017
Author(s)
Jiansong Gao, Michael R. Vissers, Joel N. Ullom, Johannes Hubmayr, Joseph W. Fowler, Leila R. Vale, Weijie Guo
We demonstrate photon counting at 1550~nm wavelength using microwave kinetic inductance detectors (MKIDs) made from TiN/Ti/TiN trilayer films with superconducting transition temperature $T_{c} \sim$ 1.4~K. The detector has a lump-element design with a

Trion Valley Coherence in Monolayer Semiconductors

May 22, 2017
Author(s)
Kai Hao, Lixiang Xu, Wu Fengcheng, Philip Nagler, Kha Tran, Xin Ma, Tobias Korn, Allan H. MacDonald, Xiaoqin Li, Galan Moody
The emerging field of valleytronics aims to exploit the valley pseudospin of electrons residing near Bloch band extrema as an information carrier. Recent experiments demonstrating optical generation and manipulation of exciton valley coherence (the

Preservation of surface conductivity and dielectric loss tangent in large-scale, encapsulated epitaxial graphene measured by non-contact microwave cavity perturbations

May 19, 2017
Author(s)
Albert F. Rigosi, Nicholas R. Glavin, Chieh-I Liu, Yanfei Yang, Jan Obrzut, Heather M. Hill, Jiuning Hu, Hsin Y. Lee, Angela R. Hight Walker, Curt A. Richter, Randolph E. Elmquist, David B. Newell
Regarding the improvement of current quantized Hall resistance (QHR) standards, one promising avenue is the growth of homogeneous monolayer epitaxial graphene (EG). A clean and simple process was used to produce large, precise areas of EG. Properties like

A practical superconducting-microcalorimeter X-ray spectrometer for beamline and laboratory science

May 16, 2017
Author(s)
William B. Doriese, Peter Abbamonte, Douglas A. Bennett, Edward V. Denison, Yizhi Fang, Daniel A. Fischer, Colin P. Fitzgerald, Joseph W. Fowler, Johnathon D. Gard, Gene C. Hilton, Cherno Jaye, Jessica L. McChesney, Luis Miaja Avila, Kelsey M. Morgan, Young Il Joe, Galen C. O'Neil, Carl D. Reintsema, Fanny Rodolakis, Daniel R. Schmidt, Hideyuki Tatsuno, Jens Uhlig, Leila R. Vale, Joel N. Ullom, Daniel S. Swetz
We describe a series of microcalorimeter X-ray spectrometers designed for a broad suite of measurement applications. The chief advantage of this type of spectrometer is that it can be orders of magnitude more efficient at collecting X-rays than more

Field Induced Spontaneous Quasiparticle Decay and Renormalization of Quasiparticle Dispersion in a Quantum Antiferromagnet

May 5, 2017
Author(s)
Tao Hong, Yiming Qiu, M. Matsumoto, D. A. Tennant, K. Coester, K. P. Schmidt, F.F. Awwadi, M. M. Turnbull, H. Agrawal, A. L. Chernyshev
We present the fine-resolution neutron scattering study in magnetic fields applied perpendicular to an easy-axis (Ising type) on the S=1/2 coupled two-leg ladder antiferromagnet (dimethylammonium)(3,5-dimethylpyridinium)CuBr 4. At finite fields, the

Metal-Insulator Transition Tuned by Magnetic Field in Bi 1.7 V 8 O 16 Hollandite

May 1, 2017
Author(s)
Amber M. Larson, Brandon Wilfong, Pouya Moetakef, Craig Brown, Peter Zavalij, Efrain E. Rodriguez
We describe a metal-insulator transition for a quasi-one dimensional system containing a mix of S = 1 and S=1/2 vanadium cations. Unlike all other known vanadates, Bi 1.7V 8O 16 displays non-spin-singlet formation upon entering the insulating state

Graphene microcapsule arrays for combinatorial electron microscopy and spectroscopy in liquids

April 27, 2017
Author(s)
Alexander Yulaev, Hongxuan Guo, Evgheni Strelcov, Lei Chen, Ivan Vlasssiouk, Andrei Kolmakov
An atomic-scale thickness, molecular impermeability, low atomic number, and mechanical strength make graphene an ideal electron transparent membrane for scanning electron microscopy and spectroscopy in liquids. Here, we present a novel sample platform made

Magnetic Properties of Epitaxial CoCr Films with Depth-Dependent Exchange-Coupling Profiles

April 27, 2017
Author(s)
Lorenzo Fallarino, Brian Kirby, Matteo Pancaldi, Patricia Riego, Andrew L. Balk, Casey W. Miller, Paolo Vavassori, A. Berger
We present a study of the compositional and temperature dependent magnetic properties of epitaxial CoCr thin films whose composition has a bathtub-like depth profile Co/Co 1→1- x cCr 0→x c/Co 1-x cCr xc /Co 1-x c→1Cr x c→0^/Co with the highest Cr

Bulklike Excitations in Nanoconfined Liquid Helium

April 20, 2017
Author(s)
M. S. Bryan, Timothy R Prisk, T. E. Sherline, S. O. Diallo, P. E. Sokol
Liquid helium confined in porous media provides a model system for studying the effects of confinement, disorder, and reduced dimensionality upon a strongly interacting Bose fluid. The effects of extreme, nanoscale confinement upon its microscopic

Electric-Field Induced Reversible Switching of the Magnetic Easy Axis in Co/BiFeO 3 on SrTiO 3

April 18, 2017
Author(s)
Tieren Gao, Xiaohang Zhang, William D. Ratcliff, Shingo Maruyama, Makoto Murakami, Anbusathaiah Varatharajan, Zahra Yamani, Peijie Chen, Ke Wang, Huairuo Zhang, Robert D. Shull, Leonid A. Bendersky, John Unguris, R. Ramesh, Ramamoorthy Ramesh, I. Takeuchi
We demonstrate reversible electric-field-induced switching of the magnetic state of the Co layer in Co/BiFeO 3 (BFO) (001) thin film heterostructures fabricated on (001) SrTiO 3 substrates. The angular dependence of the coercivity and the remanent

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 Pookpanratana, Katelyn Goetz, Ruslan Ovsyannikov, Erika Giangrisostomi, Emily Bittle, Oana Jurchescu, Steven W. Robey, Christina 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
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