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Physics

Electron physics

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  • Published Date
Displaying 76 - 100 of 179

Current-induced torques and interfacial spin-orbit coupling

December 19, 2013
Author(s)
Kyung-Jin Lee, H.-W. Lee, Aurelien Manchon, Mark D. Stiles, Paul M. Haney
In bilayer systems consisting of an ultrathin ferromagnetic layer adjacent to a metal with strong spin-orbit coupling, an applied in-plane current induces torques on the magnetization. The torques that arise from spin-orbit coupling are of particular

Dirac fermion heating, current scaling, and direct insulator-quantum Hall transition in multi-layer epitaxial graphene

August 1, 2013
Author(s)
Randolph E. Elmquist, Fan-Hung Liu, Chang-Shun Hsu, Chiashain Chuang, Tak-Pong Woo, Lung-I Huang Huang, Chi-Te Laing, Yasuhiro Fukuyama, Yanfei Yang
We have performed magnetotransport measurements on multi-layer epitaxial graphene. By increasing the driving current I through our graphene devices while keeping the bath temperature fixed, we are able to study Dirac fermion heating and current scaling in

Simultaneous Spin-Charge Relaxation in Double Quantum Dots

May 8, 2013
Author(s)
Vanita Srinivasa, Katja C. Nowack, Mohammad Shafiei, Lieven M. Vandersypen, Jacob M. Taylor
We investigate phonon-induced spin and charge relaxation mediated by spin-orbit and hyper- fine interactions for a single electron confined within a double quantum dot. A simple toy model incorporating both direct decay to the ground state of the double

Two-dimensional transport and screening in topological insulator surface states

June 6, 2012
Author(s)
Shaffique Adam, Euyheon Hwang, Sankar Das Sarma
We study the surface states of Bi2Se3 close to the topologically protected crossing point. Close to charge neutrality, local fluctuations in carrier density result in electron and hole puddles that dominate the electronic properties of these materials. By

Characteristics of Graphene for Quantized Hall Effect Measurements

June 1, 2012
Author(s)
Randolph E. Elmquist, Mariano A. Real, Irene G. Calizo, Brian G. Bush, Tian T. Shen, Nikolai N. Klimov, David B. Newell, Angela R. Hight Walker, Randall M. Feenstra
This paper describes concepts and measurement techniques necessary for characterization of graphene in the development of graphene-based quantized Hall effect (QHE) devices and resistance standards. We briefly contrast the properties of graphene produced

Electronic properties of multilayer graphene

March 31, 2012
Author(s)
Hongki Min
In this chapter, we study the electronic structure of arbitrarily stacked multilayer graphene in the absence or presence of magnetic field. Energy band structure and Landau level spectrum are obtained using a pi-orbital continuum model with nearest

Formation and structure of 360 and 540 degree domain walls in thin magnetic stripes

February 10, 2012
Author(s)
Youngman Jang, Samuel R. Bowden, Mark Mascaro, John Unguris, Caroline Ross
360˚, 540˚ and other complex transverse domain walls have been created in narrow Co wires connected to injection pads by cycling a magnetic field perpendicular to the wire length. The composite walls, formed by impingement of 180˚ transverse walls of

Graphene: Plane and Simple Electrical Metrology?

December 7, 2011
Author(s)
Randolph E. Elmquist, Felipe Hernandez-Marquez, Mariano Real, Tian T. Shen, David B. Newell, Colin J. Jacob, George R. Jones
The development of large-area graphene has direct application to electrical standards including the quantized Hall resistance because of unique characteristics not found in conventional devices. These include symmetrical conduction by electrons and holes

Mechanism for puddle formation in graphene

December 5, 2011
Author(s)
Shaffique Adam, Suyong S. Jung, Nikolai N. Klimov, Nikolai B. Zhitenev, Joseph A. Stroscio, Mark D. Stiles
Close to charge neutrality, graphene's energy landscape is highly inhomogeneous, forming a sea of electron-like and hole-like puddles that determine the properties of graphene at low carrier density. However, the details of puddle formation have remained

Graphene Production for Electrical Metrology

June 1, 2011
Author(s)
Randolph E. Elmquist, David B. Newell, George R. Jones, Felipe L. Marquez-Hernandez, Mariano A. Real, Tian T. Shen
Many material and electronic contributions must be favorable to produce devices with strong quantum Hall effect (QHE) plateaus that are suitable for precise resistance metrology. Even so, metrologically interesting QHE plateaus have been observed in

Electronic transport in two dimensional graphene

May 16, 2011
Author(s)
Shaffique Adam, Sankar Das Sarma, Euyheon Hwang, Enrico Rossi
We provide a broad review of fundamental electronic properties of two-dimensional graphene with the emphasis on density and temperature dependent carrier transport in doped or gated graphene structures. A salient feature of our review is a critical

Semiclassical Boltzmann transport theory for graphene multilayers

May 11, 2011
Author(s)
Hongki Min, Parakh Jain, Shaffique Adam, Mark D. Stiles
We calculate the conductivity of arbitrarily stacked multilayer graphene sheets within a relaxation time approximation by considering both short-range and long-range impurities. We investigate theoretically the feasibility of identifying the stacking order

Landau Levels and Band Bending in Few-Layer Epitaxial Graphene

April 18, 2011
Author(s)
Hongki Min, Shaffique Adam, Young J. Song, Joseph A. Stroscio, Mark D. Stiles, Allan H. MacDonald
The carrier density distributions in few-layer-graphene systems grown on the carbon face of silicon carbide can be radically altered by the presence of a Scanning Tunneling Microscope (STM) tip used to probe top-layer electronic properties, and by a

Perspective on Probing Metallic Ferromagnetism with Electrons

March 21, 2011
Author(s)
Daniel T. Pierce
This article presents a brief review of some of the many insights gained about metallic ferromagnetism using spin-polarized electrons as probes. Aspects of metallic ferromagnetism discussed include spin-dependent electronic structure, spin-dependent mean

Effect of interactions on edge property measurements in magnetic multilayers

February 25, 2011
Author(s)
Meng Zhu, Robert D. McMichael
This paper reports effects of inter-film interactions on static and dynamic magnetization behavior at film edges in magnetic trilayer stripe arrays under transverse applied fields. The trilayers consist of two magnetic films of Ni80Fe20, 10 nm and 20 nm

Enhanced magnetization drift velocity and current polarization in (CoFe)_{1-x}Ge_{x} alloys

February 17, 2011
Author(s)
Meng Zhu, Brian D. Soe, Robert D. McMichael, Matthew Carey, Stefan Maat, Jeffrey R. Childress
A spin wave Doppler technique is used to measure the drift velocity of the magnetization in current-carrying (CoFe)_{1-x}Ge_{x} alloys. For a current density of 10^11 A/m2, we obtain a large enhancement of drift velocity from 3.1+/-0.2 m/s for CoFe to 8.2+

Electron Vortex Beams with High Quanta of Orbital Angular Momentum

January 14, 2011
Author(s)
Benjamin James McMorran, Amit K. Agrawal, Ian M. Anderson, Andrew A. Herzing, Henri J. Lezec, Jabez J. McClelland, John Unguris
Analogous to vortices in light optical beams, electron optical beams with helical wavefronts carry orbital angular momentum and promise new capabilities for electron microscopy and other applications. We use nanofabricated diffraction holograms in an

Torsion Balance Test of Couplings to Spin

December 23, 2010
Author(s)
Blayne R. Heckel, Eric G. Adelberger, William A. Terrano, Claire E. Cramer
This article describes constraints on possible new spin-coupled interactions using a torsion pendulum with approximately 1 × 1023 polarized electrons.

Current induced torques in the presence of spin-orbit coupling

September 17, 2010
Author(s)
Paul M. Haney, Mark D. Stiles
In systems with strong spin-orbit coupling, the relationship between spin-transfer torque and the divergence of the spin current is generalized to a relation between spin transfer torques, total angular momentum current, and mechanical torques. In

Band Structure of ABC-Stacked Graphene Trilayers

July 9, 2010
Author(s)
Fan Zhang, Bhagawan Sahu, Hongki Min, Allan H. MacDonald
The ABC-stacked N-layer-graphene family of two-dimensional electron systems is described at low energies by two remarkably flat bands with Bloch states that have strongly momentum-dependent phase differences between carbon \pi-orbital amplitudes on
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