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Physics

Condensed matter

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Displaying 601 - 625 of 1253

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

Amplitude Mode in the Planar Triangular Antiferromagnet Na 0.9 MnO 2

June 5, 2018
Author(s)
Rebecca L. Dally, Yang Zhao, Zhijun Xu, Robin Chisnell, M. B. Stone, Jeffrey W. Lynn, Leon Balents, Stephen D. Wilson
Amplitude modes that arise from continuous symmetry breaking in materials are of broad interest as condensed matter analogs of the Higgs boson in particle physics. These modes reflect an oscillation in the amplitude of a complex order parameter, yet they

Anomalous Supercurrent Modulation in Josephson Junctions With Ni-Based Barriers

May 15, 2018
Author(s)
Burm Baek, Michael L. Schneider, Matthew R. Pufall, William H. Rippard
We investigate the supercurrent transport characteristics of Ni-barrier Josephson junctions with various barrier multilayer structures. Our device fabrication and magneto-electrical measurement methods provide high enough statistics and rigor necessary for

Carrier Density Control of Magnetism and Berry Phases in Doped EuTiO 3

May 10, 2018
Author(s)
Kaveh Ahadi, Zhigang Gui, Zach Porter, Jeffrey W. Lynn, Zhijun Xu, Stephen D. Wilson, Anderson Janotti, Susanne Stemmer
In materials with broken time-reversal symmetry, the Berry curvature acts as a reciprocal space magnetic field on the conduction electrons and is significant contribution to the magnetotransport properties, including to the intrinsic anomalous Hall effect

Enhanced superconducting transition temperature in electroplated rhenium

April 30, 2018
Author(s)
David P. Pappas, Don David, Mustafa Bal, Ilke Arslan, Paul T. Blanchard, Ronald B. Goldfarb, Dustin A. Hite, Hsiang S. Ku, Russell E. Lake, Junling Long, Alexana Roshko, Lee D. Pappas, Britton L. Plourde, Jianguo Wen, Xian Wu, Corey Rae H. McRae
We show that electroplated Re films in multilayers with noble metals such as Cu, Au, and Pd have an enhanced superconducting critical temperature relative to previous methods of preparing Re. The dc resistance and magnetic susceptibility indicate a critical

Magnetic Ordering in a Frustrated Bow-Tie Lattice

April 28, 2018
Author(s)
Laura J. Vera Stimpson, Efrain E. Rodriquez, Craig Brown, Gavin B. G. Stenning, Marek Jura, Donna C. Arnold
We report a systematic elastic and inelastic powder neutron diffraction study of the geometrically frustrated material, Ca 2Mn 3O 8. Ca 2Mn 3O 8 exhibits a "bow-tie" like connectivity of Mn 4+ with Ca 2+ occupying octahedral sites between MnO 6 layers

Naturally Tuned Quantum Critical Point in the S = 1 Kagome YCa 3 (VO) 3 (BO 3 ) 4

April 26, 2018
Author(s)
Harlyn J. Silverstein, Ryan Sinclair, Arzoo Sharma, Yiming Qiu, Ivo Heinmaa, Alexander Leitmae, Christopher R. Wiebe, R. Stern, Haidong Zhou
Although S = 1/2 kagome systems have been intensely studied theoretically, and within the last decade been realized experimentally, much less is known about the S = 1 analogues. While the theoretical ground state is still under debate, it has been found

Flux-tunable heat sink for quantum electric circuits

April 20, 2018
Author(s)
Matti Partanen, K-Y Tan, S Masuda, Joonas Govenius, Russell Lake, Mate Jenei, Leif Gronberg, Juha Hassel, S Simbierowicz, Visa Vesterinen, J Tuorila, T Ala-Nissila, Mikko Mottonen
Superconducting microwave circuits show great potential for practical quantum technological applications such as quantum information processing. However, fast and on-demand initialization of the quantum degrees of freedom in these devices remains a

Determination of spin Hall effect and spin diffusion length of Pt from self-consistent fitting of damping enhancement and inverse spin-orbit torque measurements

March 22, 2018
Author(s)
Andy Berger, Eric R. Edwards, Hans T. Nembach, Olof Karis, Mathias Weiler, Thomas J. Silva
Understanding the evolution of spin-orbit torque (SOT) with increasing heavy-metal thickness in ferromagnet/normal metal (FM/NM) bilayers is critical for the development of magnetic memory based on SOT. However, several experiments have revealed an

Magnetic damping in sputtered Co2MnGe Heusler compounds with A2, B2 and L21 order: Experiment and Theory

March 19, 2018
Author(s)
Justin M. Shaw, Eric R. Edwards, Martin A. Schoen, Michael L. Schneider, Matthew R. Pufall, Thomas J. Silva, Hans T. Nembach, Erna Delczeg
We show that very low values of the magnetic damping parameter can be achieved in sputter deposited poly-crystalline films of Co2MnGe annealed at relatively low temperatures ranging from 240 oC to 400 oC. Damping values as low as 0.0014 are achieved with

Local spin-wave dispersion and damping in thin yttrium-iron-garnet films

March 13, 2018
Author(s)
Rouven Dreyer, Niklas Liebing, Eric R. Edwards, Georg Woltersdorf
Using ultrafast magneto-optic sampling microscopy, we investigate the spin-wave dispersion and spin-wave damping in yttrium-iron-garnet films. With the aid of the inhomogeneous magnetic field generated by coplanar waveguides spin-waves are excited at a
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