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Articles 121 - 150 of 278
Full-Text Articles in Physics
Renormalization Of Scalar And Yukawa Field Theories With Lorentz Violation, Alejandro Ferrero, Brett David Altschul
Renormalization Of Scalar And Yukawa Field Theories With Lorentz Violation, Alejandro Ferrero, Brett David Altschul
Faculty Publications
We consider a theory of scalar and spinor fields, interacting through Yukawa and ϕ4 interactions, with Lorentz-violating operators included in the Lagrangian. We compute the leading quantum corrections in this theory. The renormalizability of the theory is explicitly shown up to one-loop order. In the pure scalar sector, the calculations can be generalized to higher orders and to include finite terms, because the theory can be solved in terms of its Lorentz-invariant version.
Photon Reconstruction In The Atlas Inner Detector And Liquid Argon Barrel Calorimeter At The 2004 Combined Test Beam, E. Abat, J. M. Abdallah, T. N. Addy, P. Adragna, M. Aharrouche, A. Ahmad, T. P. Akesson, M. Aleksa, C. Alexa, K. Anderson, A. Andreazza, F. Anghinolf, A. Antonaki, G. Arabidze, E. Arik, T. Atkinson, J. Baines, O. K. Baker, D. Banfi, S. Baron, Roberto Petti, Et. Al.
Photon Reconstruction In The Atlas Inner Detector And Liquid Argon Barrel Calorimeter At The 2004 Combined Test Beam, E. Abat, J. M. Abdallah, T. N. Addy, P. Adragna, M. Aharrouche, A. Ahmad, T. P. Akesson, M. Aleksa, C. Alexa, K. Anderson, A. Andreazza, F. Anghinolf, A. Antonaki, G. Arabidze, E. Arik, T. Atkinson, J. Baines, O. K. Baker, D. Banfi, S. Baron, Roberto Petti, Et. Al.
Faculty Publications
The reconstruction of photons in the ATLAS detector is studied with data taken during the 2004 Combined Test Beam, where a full slice of the ATLAS detector was exposed to beams of particles of known energy at the CERN SPS. The results presented show significant differences in the longitudinal development of the electromagnetic shower between converted and unconverted photons as well as in the total measured energy. The potential to use the reconstructed converted photons as a means to precisely map the material of the tracker in front of the electromagnetic calorimeter is also considered. All results obtained are compared …
Parametric Resonance Enhancement In Neutron Interferometry And Application For The Search For Non-Newtonian Gravity, Vladimir Gudkov, Hirohiko M. Shimizu, Geoffrey L. Greene
Parametric Resonance Enhancement In Neutron Interferometry And Application For The Search For Non-Newtonian Gravity, Vladimir Gudkov, Hirohiko M. Shimizu, Geoffrey L. Greene
Faculty Publications
The parametric resonance enhancement of the phase of neutrons due to non-Newtonian anomalous gravitationis considered. The existence of such resonances is confirmed by numerical calculations. A possible experimentalscheme for observing this effect is discussed based on an existing neutron interferometer design.
Limits On The Time Variation Of The Fermi Constant G_F Based On Type Ia Supernova Observations, Alejandro Ferrero, Brett David Altschul
Limits On The Time Variation Of The Fermi Constant G_F Based On Type Ia Supernova Observations, Alejandro Ferrero, Brett David Altschul
Faculty Publications
The light curve of a type Ia supernova decays at a rate set by the beta-decay lifetimes of the 56N iand Co56 produced in the explosion. This makes such a light curve sensitive to the value of the Fermi constant GF at the time of the supernova. Using data from the CfA Supernova Archive, we measure the dependence of the light curve decay rate on redshift and place a bound on the time variation of GF of |(dG_F/dt)/G_F| < 10-9 / y1.
Parity Violation In Low-Energy Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov
Parity Violation In Low-Energy Neutron-Deuteron Scattering, Young-Ho Song, Rimantas Lazauskas, Vladimir Gudkov
Faculty Publications
Parity-violating effects for low-energy elastic neutron deuteron scattering are calculated for Desplanques,Donoghue, and Holstein (DDH) and effective field theory types of weak potentials in a distorted-wave Bornapproximation, using realistic hadronic strong interaction wave functions, obtained by solving three-bodyFaddeev equations in configuration space. The resulting relation between physical observables and low-energyconstants can be used to fix low-energy constants from experiments. Potential model dependencies ofparity-violating effects are discussed.
Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason R. Hattrick-Simpers, Wilbur S. Hurst, Sesha S. Srinivasan, James E. Maslar
Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason R. Hattrick-Simpers, Wilbur S. Hurst, Sesha S. Srinivasan, James E. Maslar
Faculty Publications
An optical cell is described for high-throughput backscattering Raman spectroscopic measurements of hydrogen storagematerials at pressures up to 10 MPa and temperatures up to 823 K. High throughput is obtained by employing a 60 mm diameter × 9 mm thick sapphire window, with a corresponding 50 mm diameter unobstructed optical aperture. To reproducibly seal this relatively large window to the cell body at elevated temperatures and pressures, a gold o-ring is employed. The sample holder-to-window distance is adjustable, making this cell design compatible with optical measurement systems incorporating lenses of significantly different focal lengths, e.g., microscope objectives and single element …
Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, S. Suthirakun, Salai Cheettu Ammal, G. Xiao, Fanglin Chen, Hans-Conrad Zur Loye, Andreas Heyden
Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, S. Suthirakun, Salai Cheettu Ammal, G. Xiao, Fanglin Chen, Hans-Conrad Zur Loye, Andreas Heyden
Faculty Publications
The electronic conductivity and thermodynamic stability of mixed n-type and p-type doped SrTiO3 have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb- and Ga-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to study the effects of n- and p-doping on the electronic conductivity. In agreement with experimental observations, we find that the transformation from 20% Nb-doped Sr-deficient SrTiO3 to a non-Sr-deficient phase …
Parity Violation In The N + 3he → 3h + P Reaction: Resonance Approach, Vladimir Gudkov
Parity Violation In The N + 3he → 3h + P Reaction: Resonance Approach, Vladimir Gudkov
Faculty Publications
The method based on microscopic theory of nuclear reactions has been applied for the analysis of parityviolatingeffects in few-body systems. Different parity-violating and parity-conserving asymmetries and theirdependence on neutron energy have been estimated for the n + 3He → 3H + p reaction. The estimated effectsare in a good agreement with available exact calculations.
Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, Sumit Kewalramani, Suntao Wang, Yuan Lin, Huong Giang Nguyen, Qian Wang, Masafumi Fukuto, Lin Yang
Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, Sumit Kewalramani, Suntao Wang, Yuan Lin, Huong Giang Nguyen, Qian Wang, Masafumi Fukuto, Lin Yang
Faculty Publications
We report an experimental demonstration of a strategy for inducing two-dimensional (2D)crystallization of charged nanoparticles on oppositely charged fluid interfaces. This strategy aims to maximize the interfacial adsorption of nanoparticles, and hence their lateral packing density, by utilizing a combination of weakly charged particles and a high surface charge density on the planar interface. In order to test this approach, we investigated the assembly of cowpea mosaic virus (CPMV) on positively charged lipid monolayers at the aqueous solution surface, by means of in situX-ray scattering measurements at the liquid–vapor interface. Theassembly was studied as a function of the solution …
Modeling-Free Bounds On Nonrenormalizable Isotropic Lorentz And Cpt Violation In Qed, Brett David Altschul
Modeling-Free Bounds On Nonrenormalizable Isotropic Lorentz And Cpt Violation In Qed, Brett David Altschul
Faculty Publications
The strongest bounds on some forms of Lorentz and CPT violation come from astrophysical data, and placing such bounds may require understanding and modeling distant sources of radiation. However, it is also desirable to have bounds that do not rely on these kinds of detailed models. Bounds that do not rely on any modeling of astrophysical objects may be derived both from laboratory experiments and certain kinds of astrophysical observations. The strongest such bounds on isotropic modifications of electron, positron, and photon dispersion relations of the form E^2 = p^2 + m^ 2 + epsilon p^3 come from data on …
Doping Dependence Of Electronic And Mechanical Properties Of Gase1−XTeX And Ga1−XInXSe From First Principles, Zs. Rak, S. D. Mahanti, K. C. Mandal, N. C. Fernelius
Doping Dependence Of Electronic And Mechanical Properties Of Gase1−XTeX And Ga1−XInXSe From First Principles, Zs. Rak, S. D. Mahanti, K. C. Mandal, N. C. Fernelius
Faculty Publications
No abstract provided.
Radical Spin Helix In Two-Dimensional Electron Systems With Rashba Spin-Orbit Coupling, Yuriy V. Pershin Dr, Valeriy A. Slipko
Radical Spin Helix In Two-Dimensional Electron Systems With Rashba Spin-Orbit Coupling, Yuriy V. Pershin Dr, Valeriy A. Slipko
Faculty Publications
We suggest a long-lived spin-polarization structure, a radial spin helix, and study its relaxation dynamics. For this purpose, starting with a system of equations for spin-polarization density, we find its general solution in the axially symmetric case. It is demonstrated that the radial spin helix of a certain period relaxes slower than homogeneous spin polarization and plain spin helix. Importantly, the spin polarization at the center of the radial spin helix stays almost unchanged at short times. At longer times, when the initial nonexponential relaxation region ends, the relaxation of the radial spin helix occurs with the same time constant …
Testing Photons' Bose-Einstein Statistics With Compton Scattering, Brett David Altschul
Testing Photons' Bose-Einstein Statistics With Compton Scattering, Brett David Altschul
Faculty Publications
It is an empirical question whether photons always obey Bose-Einstein statistics, but devising and interpreting experimental tests of photon statistics can be a challenge. The nonrelativistic cross section for Compton scattering illustrates how a small admixture ν of wrong-sign statistics leads to a loss of gauge invariance; there is a large anomalous amplitude for scattering timelike photons. Nevertheless, one can interpret the observed transparency of the solar wind plasma at low frequencies as a bound ν<10−25 if Lorentz symmetry is required. If there is instead a universal preferred frame, the bound is ν<10−14, still strong compared with …
Memristive Adaptive Filters, T. Driscoll, J. Quinn, S. Klein, H. T. Kim, B. J. Kim, Yuriy V. Pershin Dr, M. Di Ventra, D. N. Basov
Memristive Adaptive Filters, T. Driscoll, J. Quinn, S. Klein, H. T. Kim, B. J. Kim, Yuriy V. Pershin Dr, M. Di Ventra, D. N. Basov
Faculty Publications
Using the memristive properties of vanadium dioxide, we experimentally demonstrate an adaptive filter by placing a memristor into an LC contour. This circuit reacts to the application of select frequency signals by sharpening the quality factor of its resonant response, and thus “learns” according to the input waveform. The proposed circuit employs only analog passive elements, and may find applications in biologically inspired processing and information storage. We also extend the learning-circuit framework mathematically to include memory-reactive elements, such as memcapacitors and meminductors, and show how this expands the functionality of adaptive memory filters.
Faddeev-Type Equations For Three-Body Symmetry Violating Scattering Amplitudes, Vladimir Gudkov, Young-Ho Song
Faddeev-Type Equations For Three-Body Symmetry Violating Scattering Amplitudes, Vladimir Gudkov, Young-Ho Song
Faculty Publications
The equations which relate three-body and two-body symmetry violating scattering amplitudes are derivedin the first order of symmetry violating interactions. They can be used to obtain three-body symmetry violatingscattering amplitudes from two-body symmetry violating scattering amplitudes calculated in low energy effectivefield theory.
Laboratory Bounds On Electron Lorentz Violation, Brett David Altschul
Laboratory Bounds On Electron Lorentz Violation, Brett David Altschul
Faculty Publications
Violations of Lorentz boost symmetry in the electron and photon sectors can be constrained by studying several different high-energy phenomenon. Although they may not lead to the strongest bounds numerically, measurements made in terrestrial laboratories produce the most reliable results. Laboratory bounds can be based on observations of synchrotron radiation, as well as the observed absences of vacuum Cerenkov radiation. Using measurements of synchrotron energy losses at LEP and the survival of TeV photons, we place new bounds on the three electron Lorentz violation coefficients c(TJ ), at the 3 x 10-13 to 6 x 10-15 levels.
Solid-State Memcapacitive System With Negative And Diverging Capacitance, J. Martinez-Rincon, M. Di Ventra, Yuriy V. Pershin Dr
Solid-State Memcapacitive System With Negative And Diverging Capacitance, J. Martinez-Rincon, M. Di Ventra, Yuriy V. Pershin Dr
Faculty Publications
We suggest a possible realization of a solid-state memory capacitive (memcapacitive) system. Our approach relies on the slow polarization rate of a medium between plates of a regular capacitor. To achieve this goal, we consider a multilayer structure embedded in a capacitor. The multilayer structure is formed by metallic layers separated by an insulator so that nonlinear electronic transport (tunneling) between the layers can occur. The suggested memcapacitor shows hysteretic charge-voltage and capacitance-voltage curves, and both negative and diverging capacitance within certain ranges of the field. This proposal can be easily realized experimentally and indicates the possibility of information storage …
Reverberation-Chamber Test Environment For Outdoor Urban Wireless Propagation Studies, Helge Fielitz, Kate A. Remley, Christopher L. Holloway, Qian Zhang, Qiong Wu, David W. Matolak
Reverberation-Chamber Test Environment For Outdoor Urban Wireless Propagation Studies, Helge Fielitz, Kate A. Remley, Christopher L. Holloway, Qian Zhang, Qiong Wu, David W. Matolak
Faculty Publications
We introduce a test environment to replicate the well-known clustering of reflections in power delay profiles arising from late-time delays and reflections. Urban wireless propagation environments are known to exhibit such clustering. The test setup combines discrete reflections generated by a fading simulator with the continuous distribution of reflections created in a reverberation chamber. We describe measurements made in an urban environment in Denver, CO, that illustrate these multiple distributions of reflections. Our comparison of measurements made in the urban environment to those made in the new test environment shows good agreement.
Far-Field Optical Nanoscopy Based On Continuous Wave Laser Stimulated Emission Depletion, C. Kuang, Wei Zhao, Guiren Wang
Far-Field Optical Nanoscopy Based On Continuous Wave Laser Stimulated Emission Depletion, C. Kuang, Wei Zhao, Guiren Wang
Faculty Publications
Stimulated emission depletion (STED) microscopy is one of the breakthrough technologies that belong to far-field optical microscopy and can achieve nanoscale spatial resolution. We demonstrate a far-field optical nanoscopy based on continuous wave lasers with different wavelengths, i.e., violet and green lasers for excitation and STED, respectively. Fluorescent dyes Coumarin 102 and Atto 390 are used for validating the depletion efficiency. Fluorescent nanoparticles are selected for characterizing the spatial resolution of the STED system. Linear scanning of the laser beams of the STED system along one line of a microscope slide, which is coated with the nanoparticles, indicates that a …
Modeling The Noble Metal/Tio2 (110) Interface With Hybrid Dft Functionals: A Periodic Electrostatic Embedded Cluster Model Study, Salai Cheettu Ammal, Andreas Heyden
Modeling The Noble Metal/Tio2 (110) Interface With Hybrid Dft Functionals: A Periodic Electrostatic Embedded Cluster Model Study, Salai Cheettu Ammal, Andreas Heyden
Faculty Publications
The interaction of Aun and Ptn (n=2,3) clusters with the stoichiometric and partially reduced rutile TiO2 (110) surfaces has been investigated using periodic slab and periodic electrostatic embedded cluster models. Compared to Au clusters, Pt clusters interact strongly with both stoichiometric and reduced TiO2 (110) surfaces and are able to enhance the reducibility of the TiO2 (110) surface, i.e., reduce the oxygen vacancy formation energy. The focus of this study is the effect of Hartree–Fock exchange on the description of the strength of chemical bonds at the interface of Au/Pt clusters and the TiO2 (110) surface. Hartree–Fock exchange helps describing …
Dynamic Path Bifurcation For The Beckmann Reaction: Observation And Implication, H. Yamataka, M. Sato, H. Hasegawa, Salai Cheettu Ammal
Dynamic Path Bifurcation For The Beckmann Reaction: Observation And Implication, H. Yamataka, M. Sato, H. Hasegawa, Salai Cheettu Ammal
Faculty Publications
The reaction of oximes to amides, known as the Beckmann rearrangement, may undergo fragmentation to form carbocations + nitriles instead of amides when the cations have reasonable stability. The reactions of oxime derivatives of 1-substituted-phenyl-2-propanones and 3-substituted-phenyl-2-butanones in aqueous solvents gave both rearrangement and fragmentation products, the ratio of which was dependent on substituents. Transition state (TS) optimizations and intrinsic reaction coordinate (IRC) calculations for the reaction of 1-phenyl-2-propanone oximes showed that there is a single TS for each substituted compound. The IRC path from the TS either led to a rearrangement product or a fragmentation product depending on the …
Lorentz Violation With An Antisymmetric Tensor, Brett David Altschul, Quentin G. Bailey, Alan Kostelecky
Lorentz Violation With An Antisymmetric Tensor, Brett David Altschul, Quentin G. Bailey, Alan Kostelecky
Faculty Publications
Field theories with spontaneous Lorentz violation involving an antisymmetric 2-tensor are studied. A general action including nonminimal gravitational couplings is constructed, and features of the Nambu-Goldstone and massive modes are discussed. Minimal models in Minkowski spacetime exhibit dualities with Lorentz-violating vector and scalar theories. The post-Newtonian expansion for nonminimal models in Riemann spacetime involves qualitatively new features, including the absence of an isotropic limit. Certain interactions producing stable Lorentz-violating theories in Minkowski spacetime solve the renormalization-group equations in the tadpole approximation.
A Measurement Of Coherent Neutral Pion Production In Neutrino Neutral Current Interactions In The Nomad Experiment, C. T. Kullenberg, S. R. Mishra, M. B. Seaton, J. J. Kim, X. C. Tian, A. M. Scott, M. Kirsanov, 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, Et. Al.
A Measurement Of Coherent Neutral Pion Production In Neutrino Neutral Current Interactions In The Nomad Experiment, C. T. Kullenberg, S. R. Mishra, M. B. Seaton, J. J. Kim, X. C. Tian, A. M. Scott, M. Kirsanov, 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, Et. Al.
Faculty Publications
We present a study of exclusive neutral pion production in neutrino–nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to 1.44 X 106 muon-neutrino Charged Current interactions in the energy range 2.5 ≤ E v & ≤ 300GeV. Neutrino events with only one visible π0 in the final state are expected to result from two Neutral Current processes: coherent π0 production, v + A
Radiatively Induced Lorentz And Gauge Symmetry Violation In Electrodynamics With Varying Alph A, Alejandro Ferrero, Brett David Altschul
Radiatively Induced Lorentz And Gauge Symmetry Violation In Electrodynamics With Varying Alph A, Alejandro Ferrero, Brett David Altschul
Faculty Publications
A time-varying fine structure constant α(t) could give rise to Lorentz- and CPT-violating changes to the vacuum polarization, which would affect photon propagation. Such changes to the effective action can violate gauge invariance, but they are otherwise permitted. However, in the minimal theory of varying α, no such terms are generated at lowest order. At second order, vacuum polarization can generate an instability—a Lorentz-violating analogue of a negative photon mass squared −m2γ∝α(˙α2α)2log(Λ2), where Λ is the cutoff for the low-energy effective theory.
Memristive Model Of Amoeba Learning, Yuriy V. Pershin Dr, Steven La Fontaine, Massimiliano Di Ventra
Memristive Model Of Amoeba Learning, Yuriy V. Pershin Dr, Steven La Fontaine, Massimiliano Di Ventra
Faculty Publications
Recently, it was shown that the amoebalike cell Physarum polycephalum when exposed to a pattern of periodic environmental changes learns and adapts its behavior in anticipation of the next stimulus to come. Here we show that such behavior can be mapped into the response of a simple electronic circuit consisting of a LC contour and a memory-resistor (a memristor) to a train of voltage pulses that mimic environment changes. We also identify a possible biological origin of the memristive behavior in the cell. These biological memory features are likely to occur in other unicellular as well as mutlicellular organisms, albeit …
Spin Polarization Control By Electric Stirring: Proposal For A Spintronic Device, Yuriy V. Pershin Dr, N. A. Sinitsyn, A. Kogan, A. Saxena, D. L. Smith
Spin Polarization Control By Electric Stirring: Proposal For A Spintronic Device, Yuriy V. Pershin Dr, N. A. Sinitsyn, A. Kogan, A. Saxena, D. L. Smith
Faculty Publications
We propose a spintronic device to generate spin polarization in a mesoscopic region by purely electric means. We show that the spin Hall effect in combination with the stirring effect are sufficient to induce measurable spin polarization in a closed geometry. Our device structure does not require the application of magnetic fields, external radiation or ferromagnetic leads, and can be implemented in standard semiconducting materials.
Probability Density Functions For Snir In Ds-Cdma, David W. Matolak
Probability Density Functions For Snir In Ds-Cdma, David W. Matolak
Faculty Publications
Analytical expressions for the probability density function of block-wise signal-to-noise-plus-interference ratio for both synchronous and asynchronous direct-sequence spread spectrum code-division multiple access systems are developed, for equal average energy signals on the Gaussian and Rayleigh flat fading channels. Using the standard Gaussian approximation for multi-user interference, accurate density approximations are obtained, which agree very well with computer simulation results.
Bounding Isotropic Lorentz Violation Using Synchrotron Losses At Lep, Brett David Altschul
Bounding Isotropic Lorentz Violation Using Synchrotron Losses At Lep, Brett David Altschul
Faculty Publications
Some deviations from special relativity—especially isotropic effects—are most efficiently constrained using particles with velocities very close to 1. While there are extremely tight bounds on some of the relevant parameters coming from astrophysical observations, many of these rely on our having an accurate understanding of the dynamics of these high-energy sources. It is desirable to have reliable laboratory constraints on these same parameters. The fastest-moving particles in a laboratory were electrons and positrons at LEP. The energetics of the LEP beams were extremely well understood, and measurements of the synchrotron emission rate indicate that the isotropic Lorentz violation coefficient |˜κ …
Frequency Doubling And Memory Effects In The Spin Hall Effect, Yuriy V. Pershin Dr, Massimiliano Di Ventra
Frequency Doubling And Memory Effects In The Spin Hall Effect, Yuriy V. Pershin Dr, Massimiliano Di Ventra
Faculty Publications
We predict that when an alternating voltage is applied to a semiconducting system with inhomogeneous electron density in the direction perpendicular to main current flow, the spin Hall effect results in a transverse voltage containing a double-frequency component. We also demonstrate that there is a phase shift between applied and transverse-voltage oscillations, related to the general memristive behavior of semiconductor spintronic systems. A different method to achieve frequency doubling based on the inverse spin Hall effect is also discussed.
Macrospin Model To Explain The Absence Of Preswitching Oscillations In Magnetic Tunnel Junctions: Fieldlike Spin-Transfer Torque, Samir Garzon, Yaroslaw Bazaliy, Richard A. Webb, Mark Covington, Shehzaad Kaka, Thomas M. Crawford
Macrospin Model To Explain The Absence Of Preswitching Oscillations In Magnetic Tunnel Junctions: Fieldlike Spin-Transfer Torque, Samir Garzon, Yaroslaw Bazaliy, Richard A. Webb, Mark Covington, Shehzaad Kaka, Thomas M. Crawford
Faculty Publications
We show that the absence of preswitching oscillations (“incubation delay”) in magnetic tunnel junctions can be explained within the macrospin model by a sizable fieldlike component of the spin-transfer torque. It is further suggested that measurements of the voltage dependence of tunnel junction switching time in the presence of external easy axis magnetic fields can be used to determine the magnitude and voltage dependence of the fieldlike torque.