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Articles 1 - 11 of 11
Full-Text Articles in Physics
Coherent Control Of Nanomagnet Dynamics Via Ultrafast Spin Torque Pulses, Samir Garzon, Longfei Ye, Richard A. Webb, Thomas M. Crawford, Mark Covington, Shehzaad Kaka
Coherent Control Of Nanomagnet Dynamics Via Ultrafast Spin Torque Pulses, Samir Garzon, Longfei Ye, Richard A. Webb, Thomas M. Crawford, Mark Covington, Shehzaad Kaka
Faculty Publications
We demonstrate reliable manipulation of the magnetization dynamics of a precessing nanomagnet by precisely controlling the spin transfer torque on the subnanosecond time scale. Using a simple pulse shaping scheme consisting of two ultrafast spin torque pulses with variable amplitudes and delay, we demonstrate coherent control over the precessional orbits and the ability to tune the switching probability of a nanomagnet at room temperature and 77 K. Our measurements suggest that appropriately shaped spin transfer can be used to efficiently manipulate the orientation of a free layer nanomagnet, thus providing an alternative for spin torque driven spintronic devices.
Spin Memristive Systems: Spin Memory Effects In Semiconductor Spintronics, Yuriy V. Pershin Dr, M. Di Ventra
Spin Memristive Systems: Spin Memory Effects In Semiconductor Spintronics, Yuriy V. Pershin Dr, M. Di Ventra
Faculty Publications
Recently, in addition to the well-known resistor, capacitor, and inductor, a fourth passive circuit element, named memristor, has been identified following theoretical predictions. The model example used in such case consisted in a nanoscale system with coupled ionic and electronic transport. Here, we discuss a system whose memristive behavior is based entirely on the electron-spin degree of freedom, which allows for a more convenient control than the ionic transport in nanostructures. An analysis of time-dependent spin transport at a semiconductor/ferromagnet junction provides a direct evidence of memristive behavior. Our scheme is fundamentally different from previously discussed schemes of memristive systems …
Effective Single-Particle Order-N Scheme For The Dynamics Of Open Noninteracting Many-Body Systems, Yuriy V. Pershin Dr, Y. Dubi, M. Di Ventra
Effective Single-Particle Order-N Scheme For The Dynamics Of Open Noninteracting Many-Body Systems, Yuriy V. Pershin Dr, Y. Dubi, M. Di Ventra
Faculty Publications
Quantum master equations are common tools to describe the dynamics of many-body systems open to an environment. Due to the interaction with the latter, even for the case of noninteracting electrons, the computational cost to solve these equations increases exponentially with the partical number. We propose a simple scheme, which allows to study the dynamics of N noninteracting electrons taking into account both dissipation effects and Fermi statistics, with a computational cost that scales linearly with N. Our method is based on a mapping of the many-body system to a specific set of effective single-particle systems. We provide detailed …
Community Detection In Complex Networks By Dynamical Simplex Evolution, Vladimir Gudkov, V. Montealegre, S. Nussinov, Z. Nussinov
Community Detection In Complex Networks By Dynamical Simplex Evolution, Vladimir Gudkov, V. Montealegre, S. Nussinov, Z. Nussinov
Faculty Publications
We benchmark the dynamical simplex evolution (DSE) method with several of the currently available algorithms to detect communities in complex networks by comparing correctly identified nodes for different levels of "fuzziness" of random networks composed of well-defined communities. The potential benefits of the DSE method to detect hierarchical substructures in complex networks are discussed.
A High Resolution Neutrino Experiment In A Magnetic Field For Project-X At Fermilab, Sanjib R. Mishra, Roberto Petti, Carl Rosenfeld
A High Resolution Neutrino Experiment In A Magnetic Field For Project-X At Fermilab, Sanjib R. Mishra, Roberto Petti, Carl Rosenfeld
Faculty Publications
We propose a new high-resolution neutrino experiment within a dipole magnetic field, HiResMν. This experiment will run along with long-baseline neutrino oscillation experiments (LBLν) such as NOνA, a large-cavity detector at DUSEL, or a Liquid-Argon detector in the Medium-Energy (ME) configuration of the NuMI-beam. Assuming the 120 GeV Main Injector proton intensities we anticipate 140(50) million νμ (⊽μ) Charged-Current (CC) events in the fiducial volume, for 3(4)-year run with the ME (anti)neutrino beam. Alternatively, the same statistics could be collected in just 1(1.5) year with the High Energy (HE) beam configuration. …
Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li
Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li
Faculty Publications
Hydrogen atmosphere can significantly change the tribological behavior at diamond and diamondlike carbon (DLC) surfaces and the friction-reducing effect depends on the partial pressure of hydrogen. We combined density functional theory modeling and thermodynamic quantities to predict the equilibrium partial pressures of hydrogen at temperature T, PH2 (T), for a fully atomic hydrogen passivated diamondsurface. Above the equilibrium PH2 (T), ultralow friction can be achieved at diamond and DLC surfaces. The calculation agrees well with friction tests at various testing conditions. We also show that PH2 (T) …
Asymmetry Of Recoil Protons In Neutron Β Decay, Vladimir Gudkov
Asymmetry Of Recoil Protons In Neutron Β Decay, Vladimir Gudkov
Faculty Publications
A complete analysis of proton recoil asymmetry in neutron decay in the first order of radiative and recoil corrections is presented. The possible contributions from new physics are calculated in terms of low energy coupling constants, and the sensitivity of the measured asymmetry to models beyond the Standard Model are discussed.
Current-Voltage Characteristics Of Semiconductor/Ferromagnet Junctions In The Spin-Blockade Regime, Yuriy V. Pershin Dr, Massimiliano Di Ventra
Current-Voltage Characteristics Of Semiconductor/Ferromagnet Junctions In The Spin-Blockade Regime, Yuriy V. Pershin Dr, Massimiliano Di Ventra
Faculty Publications
It was recently predicted [Phys. Rev. B, 193301 (2007)] that spin blockade may develop at nonmagnetic semiconductor/perfect ferromagnet junctions when the electron flow is directed from the semiconductor into the ferromagnet. Here we consider current-voltage characteristics of such junctions. By taking into account the contact resistance, we demonstrate a current stabilization effect: by increasing the applied voltage, the current density through the junction saturates at a specific value. The transient behavior of the current density is also investigated. We show that an abrupt change in the applied voltage is accompanied by a spike in the current density. It is anticipated …
A Precise Measurement Of The Muon Neutrino–Nucleon Inclusive Charged Current Cross Section Off An Isoscalar Target In The Energy Range 2.5 < EV < 40 Gev By Nomad, Nomad Collaboration, Q. Wu, S. R. Mishra, A. Godley, Roberto Petti, S. Alekhin, P. Astier, D. Autiero, A. Baldisseri, M. Baldo-Ceolin, M. Banner, G. Bassompierre, K. Benslama, N. Besson, I. Bird, B. Blumenfeld, F. Bobisut, J. Bouchez, S. Boyd, A. Bueno, Et. Al.
A Precise Measurement Of The Muon Neutrino–Nucleon Inclusive Charged Current Cross Section Off An Isoscalar Target In The Energy Range 2.5 < EV < 40 Gev By Nomad, Nomad Collaboration, Q. Wu, S. R. Mishra, A. Godley, Roberto Petti, S. Alekhin, P. Astier, D. Autiero, A. Baldisseri, M. Baldo-Ceolin, M. Banner, G. Bassompierre, K. Benslama, N. Besson, I. Bird, B. Blumenfeld, F. Bobisut, J. Bouchez, S. Boyd, A. Bueno, Et. Al.
Faculty Publications
We present a measurement of the muon neutrino–nucleon inclusive charged current cross section, off an isoscalar target, in the neutrino energy range 2.5⩽Ev ⩽ 40GeV. The significance of this measurement is its precision, ±4% in 2.5⩽Ev ⩽ 10GeV, and ± 2.6% in 10⩽Ev ⩽ 40GeV regions, where significant uncertainties in previous experiments still exist, and its importance to the current and proposed long baseline neutrino oscillation experiments.
Combinatorial Investigation Of Magnetostriction In Fe-Fa And Fe-Ga-Al, Jason R. Hattrick-Simpers, Dwight Hunter, Corneliu M. Craciunescu, Kyu Sung Jang, Makoto Murakami, James Cullen, Manfred Wuttig, Ichiro Takeuchi, Samuel E. Lofland, Leonid Bendersky, Noble Woo, Robert Bruce Vandover, Toshiya Takahashi, Yasubumi Furuya
Combinatorial Investigation Of Magnetostriction In Fe-Fa And Fe-Ga-Al, Jason R. Hattrick-Simpers, Dwight Hunter, Corneliu M. Craciunescu, Kyu Sung Jang, Makoto Murakami, James Cullen, Manfred Wuttig, Ichiro Takeuchi, Samuel E. Lofland, Leonid Bendersky, Noble Woo, Robert Bruce Vandover, Toshiya Takahashi, Yasubumi Furuya
Faculty Publications
A high-throughput high-sensitivity optical technique for measuringmagnetostriction of thin-film composition-spread samples has been developed. It determines the magnetostriction by measuring the induced deflection of micromachined cantilever unimorph samples. Magnetostrictionmeasurements have been performed on as-deposited Fe–Ga and Fe–Ga–Al thin-film composition spreads. The thin-film Fe–Ga spreads display a similar compositional variation of magnetostriction as bulk. A previously undiscovered peak in magnetostriction at low Ga content was also observed and attributed to a maximum in the magnetocrystalline anisotropy. Magnetostrictive mapping of the Fe–Ga–Al ternary system reveals the possibility of substituting up to 8at.%Al in Fe70Ga30 without significant degradation of magnetostriction.
High-Throughput Screening Of Shape Memory Alloy Thin-Film Spreads Using Nanoindentation, Arpit Dwivedi, Thomas J. Wyrobek, Oden L. Warren, Jason R. Hattrick-Simpers, Olubenga O. Famodu, Ichiro Takeuchi
High-Throughput Screening Of Shape Memory Alloy Thin-Film Spreads Using Nanoindentation, Arpit Dwivedi, Thomas J. Wyrobek, Oden L. Warren, Jason R. Hattrick-Simpers, Olubenga O. Famodu, Ichiro Takeuchi
Faculty Publications
We have demonstrated the utility of nanoindentation as a rapid characterization tool for mapping shape memoryalloy compositions in combinatorial thin-film libraries. Nanoindentation was performed on Ni–Mn–Al ternary composition spreads. The indentation hardness and the reduced elastic modulus were mapped across a large fraction of the ternary phase diagram. The large shape memoryalloy composition region, located around the Heusler composition (Ni2MnAl), was found to display significant departure in these mechanical properties from the rest of the composition spread. In particular, the modulus and the hardness values are lower for the martensite region than those of the rest of the …