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Displaying 576 - 600 of 1240

Phase-Sensitive Small-Angle Neutron Scattering Experiment

September 19, 2018
Author(s)
Erik Brok, Kathryn L. Krycka, Erika C. Vreeland, Andrew Gomez, Dale L. Huber, Charles Majkrzak
Small angle neutron scattering is a useful technique for determining the structure of biomolecules in solution. However, because of the well-known problem that the phase of the scattered wave is lost in scattering experiments, unambiguous structural

Topological Transitions Induced by Antiferromagnetism in a Thin-Film Topological Insulator

August 29, 2018
Author(s)
Qing Lin He, Gen Yin, Luyan Yu, Alexander Grutter, Lei Pan, Chui-Zhen Chen, Xiaoyu Che, Guoqiang Yu, Bin Zhang, Qiming Shao, Alexander L. Stern, Brian Casas, Jing Xia, Xiaodong Han, Brian Kirby, Roger K. Lake, K. T. Law, Kang L. Wang
Ferromagnetism in topological insulators (TIs) opens a topologically non-trivial exchange band gap, providing an exciting platform for manipulating the topological order through external magnetic field. Here, we experimentally show that the surface of an

Part-per-million quantization and current-induced breakdown of the quantum anomalous Hall effect

August 27, 2018
Author(s)
Eli J. Fox, Ilan T. Rosen, Yanfei Yang, George R. Jones Jr., Randolph Elmquist, Xufeng Kou, Lei Pan, Kang L. Wang, D. Goldhaber-Gordon
In the quantum anomalous Hall effect, quantized Hall resistance and vanishing longitudinal resistivity are predicted to result from the presence of dissipationless, chiral edge states and an insulating two-dimensional bulk, without requiring an external

Phase Modulators Based on High Mobility Ambipolar ReSe2 Field-Effect Transistors

August 24, 2018
Author(s)
Nihar Pradhan, Carlos Garcia, Bridget Isenberg, Daniel Rhodes, Simin Feng, Shariar Memaran, Yan Xin, Amber McCreary, Angela R. Hight Walker, Aldo Raeliarijaona, Humberto Terrones, Mauricio Terrones, Steve McGill, Luis Balicas
We fabricated ambipolar field-effect transistors (FETs) from multi-layered triclinic ReSe2, mechanically exfoliated onto a SiO2 layer grown on p-doped Si. In contrast to previous reports on thin layers (2 to 3 layers), we extract field-effect carrier

A 300-mK Test Bed for Rapid Characterization of Microwave SQUID Multiplexing Circuits

August 3, 2018
Author(s)
Abigail L. Wessels, Daniel T. Becker, Douglas A. Bennett, Johnathon D. Gard, Johannes Hubmayr, Norman Jarosik, Vincent Y. Kotsubo, John A. Mates, Joel N. Ullom
Microwave SQUID multiplexing is a promising technique for multiplexing large arrays of transition edge sensors. A major bottleneck in the development and distribution of microwave SQUID multiplexer chips occurs in the time-intensive design testing and

Low-Temperature Detectors for CMB Imaging Arrays

August 3, 2018
Author(s)
Johannes Hubmayr, Jason E. Austermann, James A. Beall, Daniel T. Becker, Bradley J. Dober, Shannon M. Duff, Jiansong Gao, Gene C. Hilton, Christopher M. McKenney, Joel N. Ullom, Jeffrey L. Van Lanen, Michael R. Vissers
We review advances in low-temperature detector (LTD) arrays for cosmic microwave background (CMB) polarization experiments, with a particular emphasis on imaging arrays. We briefly motivate the science case, which has spurred a large number of independent

Nanoscale Magnetic Localization in Exchange Strength Modulated Ferromagnets

August 3, 2018
Author(s)
Brian J Kirby, L. Fallarino, P. Riego, Brian B. Maranville, Casey W. Miller, A. Berger
Compositional grading can be used to continuously vary the "local" Curie temperature across the thickness of a ferromagnetic alloy thin film, allowing for a continuously moveable vertical boundary between strongly and weakly magnetized regions. The utility

Competitive solvation effects in polyelectrolyte solutions

August 1, 2018
Author(s)
Alexandros Chremos, Jack F. Douglas
An understanding of the solution properties and phase behavior of natural and synthetic polyelectrolytes requires an understanding of the competitive association of water (“hydration”) and ion association to the polymer backbone and the consequences of

Towards superconductivity in p-type delta-doped Si/Al/Si heterostructures

July 30, 2018
Author(s)
Aruna N. Ramanayaka, Hyun Soo Kim, Joseph A. Hagmann, Roy E. Murray, Ke Tang, Neil M. Zimmerman, Curt A. Richter, Joshua M. Pomeroy, Frederick Meisenkothen, Huairuo Zhang, Albert Davydov, Leonid A. Bendersky
In pursuit of superconductivity in p-type silicon (Si), we are using a single atomic layer of aluminum (Al) sandwiched between a Si substrate and a thin Si epi-layer. The delta layer was fabricated starting from an ultra high vacuum (UHV) flash anneal of

A Spin-1 Representation for Dual-Funnel Energy Landscapes

July 20, 2018
Author(s)
Justin E. Elenewski, Kirill Velizhanin, Michael P. Zwolak
The interconversion between left- and right-handed helical folds of a polypeptide defines a dual-funneled free energy landscape. In this context, the funnel minima are connected through a continuum of unfolded conformations, evocative of the classical

Epitaxial graphene for quantum resistance metrology

July 20, 2018
Author(s)
Mattias Kruskopf, Randolph Elmquist
A new generation of graphene-based quantum Hall resistance standards promises high precision for the unit ohm under relaxed measurement conditions, enabling the use of compact measurement systems. To meet the requirements of metrological applications

Exchange-Biasing Topological Charges by Antiferromagnetism

July 17, 2018
Author(s)
Qing Lin He, Gen Yin, Alexander Grutter, Lei Pan, Xiaoyu Che, Guoqiang Yu, Dustin A. Gilbert, Steven M. Disseler, Yizhou Liu, Padraic Shafer, Bin Zhang, Yingying Wu, Brian Kirby, Elke Arenholz, Roger K. Lake, Xiaodong Han, Kang L. Wang, Xiaodong Han, Kang L. Wang
'Geometric' or 'topological' Hall effect is induced by the emergent gauge field experienced by the carriers adiabatically passing through chiral spin textures. This effect is an indication of non-trivial spin textures, such as magnetic skyrmions. Here we

Mechanisms for carbon adsorption on Au(110)-(2 x 1): A work function analysis

July 17, 2018
Author(s)
Dustin A. Hite, Hossein Jooya, Kyle S. McKay, Eunja Kim, Philippe F. Weck, David P. Pappas, H.R. Sadeghpour
The variation of the work function upon carbon adsorption on the reconstructed Au(110) surface is measured experimentally and compared to density functional calculations. The adsorption dynamics is simulated with ab-initio molecular dynamics techniques

Energy-level statistics in strongly disordered systems with power-law hopping

July 16, 2018
Author(s)
Paraj T. Bhattacharjee, Victor L. Quito, Sergey V. Syzranov
Motivated by neutral excitations in disordered electronic materials and systems of trapped ultracold particles with long-range interactions, we study energy-level statistics of quasiparticles with the power-law hopping Hamiltonian $\propto 1/r^\alpha$ in a

Quantum transport in graphene p-n junctions with Moire superlattice modulation

July 12, 2018
Author(s)
Jiuning Hu, Albert Rigosi, Ji Ung Lee, Hsin Y. Lee, Yanfei Yang, Chieh-I Liu, Randolph Elmquist, David B. Newell
This work presents simulations of quantum transport in graphene p-n junctions (pnJs) in which Moire superlattice potentials are incorporated to demonstrate the interplay of the effect of pnJs and Moire superlattice potentials. It is shown that the

Polyelectrolyte association and solvation

July 10, 2018
Author(s)
Alexandros Chremos, Jack F. Douglas
There has been significant interest in the tendency of highly charged particles having the same charge to form dynamic clusters in solution, but an accepted theoretical framework that can account for this ubiquitous phenomenon has been slow to develop. The

The Nature of Spin Excitations in the One-Third Magnetization Plateau Phase of Ba 3 CoSb 2 O 9

July 10, 2018
Author(s)
Y. Kamiya, L. Ge, Tao Hong, Yiming Qiu, D. L. Quintero-Castro, Z. Lu, H. B. Cao, M. Matsuda, E. S. Choi, C. D. Batista, M. Mourigal, H. D. Zhou, J. Ma
A recent experiment revealed that the spin-1/2 triangular-lattice Heisenberg antiferromagnet Ba 3CoSb 2O 9 is a magnetically ordered material with an anomalous excitation spectrum, comprising a high-intensity excitation continuum and short-lived magnons

Epitaxial Graphene for High-Current QHE Resistance Standards

July 9, 2018
Author(s)
Mattias Kruskopf, Jiuning Hu, Bi Y. Wu, Yanfei Yang, Hsin Y. Lee, Albert F. Rigosi, David B. Newell, Randolph E. Elmquist
We report the growth of large-area monolayer graphene on the centimeter scale using an optimized growth process allowing for reproducibility and morphology improvements. Magneto-transport measurements on graphene quantum Hall effect devices demonstrate the

Epitaxial Graphene p-n Junctions

July 9, 2018
Author(s)
Jiuning Hu, Mattias Kruskopf, Yanfei Yang, Bi Y. Wu, Jifa Tian, Alireza R. Panna, Albert F. Rigosi, Hsin Y. Lee, George R. Jones Jr., Marlin E. Kraft, Dean G. Jarrett, Kenji Watanabe, Takashi Taniguchi, Randolph E. Elmquist, David B. Newell
We report the fabrication and measurement of top gated epitaxial graphene p-n junctions where exfoliated hexgonal boron nitride (hBN) is used as the gate dielectric. The four terminal longitudinal resistance across a single junction is well quantized at R_

Local Quantum Phase Transition in YFe 2 Al^d10

July 3, 2018
Author(s)
W. J. Gannon, L. S. Wu, I. A. Zaliznyak, W. H. Xu, A. M. Tsvelik, Yiming Qiu, Jose Rodriguez Rivera, M. C. Aronson
A phase transition occurs when correlated regions of a new phase grow to span the system and the fluctuations within the correlated regions become long-lived. Here we present neutron scattering measurements showing that this conventional picture must be

Non-tunneling origin of the 1/f noise in SiC MOSFET

July 1, 2018
Author(s)
Kin (Charles) Cheung, Jason Campbell
Abstract: It has long been established that MOSFET random telegraph noise and the cumulative 1/f noise is the result of inversion charge tunneling in and out of bulk traps in the gate oxide near the interface. The tunneling nature is a key concept upon

Coexistence of Superconductivity and Short-Range Double-Stripe Spin Correlations in Te-Vapor Annealed FeTe 1-x Se x (X less than or equal to} 0.2)

June 14, 2018
Author(s)
Zhijun Xu, J. A. Schneeloch, Ming Yi, Yang Zhao, Masaaki Matsuda, D. M. Pajerowski, Songxue Chi, R. J. Birgeneau, Genda Gu, J. M. Tranquada, Guangyong Xu
In as-grown bulk crystals of Fe 1+yTe 1-xSe x with x less than or equal to} 0.3, excess Fe (y>0) is inevitable and correlates with a suppression of superconductivity. At the same time, there remains the question as to whether the character of the
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