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Search Publications by: Mark D. Stiles (Fed)

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Displaying 126 - 150 of 202

Boltzmann Test of Slonczewski's Theory of Spin Transfer Torque

November 12, 2004
Author(s)
J Xiao, A Zangwill, Mark D. Stiles
We use a matrix Boltzmann equation formalism to test the accuracy of Slonczewski's theory of spin-transfer torque in thin-film heterostructures where a non-magnetic spacer layer separates two non-collinear ferromagnetic layers connected to non-magnetic

Current-driven switching in a single exchange-biased ferromagnetic layer

July 9, 2004
Author(s)
Tingyong Chen, Yi Ji, C Chien, Mark D. Stiles
We demonstrate spin-transfer torque effects in a single exchange-biased ferromagnetic layer. A current through a point contact to the exchange-biased Co layer reverses the magnetization of a nanodomain in the layer hysteretically for low applied magnetic

Artifacts in Ballistic Magnetoresistance Measurements

June 1, 2004
Author(s)
William F. Egelhoff Jr., L Gan, H Ettedgui, Y Kadmon, Cedric J. Powell, P J. Chen, Alexander J. Shapiro, Robert McMichael, J Mallett, Thomas P. Moffat, Mark D. Stiles, Erik B. Svedberg
We have studied the behavior of electrodeposited Ni and Fe nanocontacts in magnetic fields and the changes in resistivity (Δ}R) that occur. Metallic particles suspended in plating solution, created and collected from the electroplating bath of a

Artifacts in Ballistic Magnetoresistance Measurements

June 1, 2004
Author(s)
William F. Egelhoff Jr., L Gan, H Ettendgui, Y Kadmon, Cedric J. Powell, P J. Chen, Alexander J. Shapiro, Robert McMichael, J Mallett, Thomas P. Moffat, Mark D. Stiles
We have carried out an extensive search for credible evidence to support the existence of a ballistic magnetoresistance (BMR) effect in magnetic nanocontacts. We have investigated both thin-film and thin-wire geometries for both mechanically-formed and

Spin Nomenclature for Semiconductors and Magnetic Metals

June 1, 2004
Author(s)
B Jonker, A Hanbicki, Daniel T. Pierce, Mark D. Stiles
The different conventions used in the semiconductor and magnetic metals communities can cause confusion in the context of spin polarization and transport in simple heterostructures. In semiconductors, terminology is based on the orientation of the electron

Phenomenological Theory of Current-Induced Magnetization Precession

February 13, 2004
Author(s)
Mark D. Stiles, J Xiao, A Zangwill
We solve appropriate drift-diffusion and Landau-Lifshitz-Gilbert equations to demonstrate that unpolarized current flow from a non-magnet into a ferromagnet can produce a precession-type instability of the magnetization. The fundamental origin of the

Artifacts that mimic ballistic magnetoresistance

January 1, 2004
Author(s)
William F. Egelhoff Jr., L Gan, Erik B. Svedberg, Cedric J. Powell, Alexander J. Shapiro, Robert McMichael, J Mallett, Thomas P. Moffat, Mark D. Stiles
We have investigated the circumstances underlying recent reports of very large values of ballistic magnetoresistance (BMR) in nanocontacts between magnetic wires. We find that the geometries used are subject to artifacts due to motion of the wires that

Coercivities above 10 kOe in CoPd Superlattices

January 1, 2004
Author(s)
William F. Egelhoff Jr., Cedric J. Powell, L Gan, P J. Chen, H Ettendgui, D Tirosh, Robert McMichael, Mark D. Stiles, J Mallett, Alexander J. Shapiro, John E. Bonevich
We have achieved excellent grain isolation in CoPd superlattices by using 10 nm Au as both an underlayer and an overlayer and diffusing Au into the grain boundaries by annealing for approximately equal to} 30 min. at 300 degrees C. The grain isolation

Real-Space Imaging of Structural Transitions in the Vortex Lattice of V 3 Si

October 6, 2003
Author(s)
C Sosolik, Joseph A. Stroscio, Mark D. Stiles, E Hudson, Steven R. Blankenship, Aaron P. Fein, Robert Celotta
The predictions of nonlocal London theory are confirmed by real-space measurements of the hexagonal to nearly square transition in the vortex lattice structure of V 3Si. We observe that the lattice transforms from hexagonal to nearly square over the field

Current-Induced Spin-Wave Excitations in a Single Ferromagnetic Layer

May 1, 2003
Author(s)
Yi Ji, C L. Chien, Mark D. Stiles
Evidence for a current induced spin-transfer torque effect has been investigated in a series of point contacts to single ferromagnetic layers. At specific current densities, abrupt resistance changes, similar to those attributed to current-induced spin

Current-Induced Spin-Wave Excitations in a Single Ferromagnetic Layer

March 14, 2003
Author(s)
Yi Ji, C Chien, Mark D. Stiles
Evidence for a current induced spin-transfer torque effect has been investigated in a series of point contacts to single ferromagnetic layers. At specific current densities, abrupt resistance changes, similar to those attributed to current-induced spin

Anatomy of Spin-Transfer Torque

July 1, 2002
Author(s)
Mark D. Stiles, A Zangwill
Spin-transfer torques occur in magnetic heterostructures because the transverse component of a spin current that flows from a non-magnet into a ferromagnet is absorbed at the interface. We demonstrate this fact explicitly using free electron models and

Spin Polarization of Injected Electrons

May 17, 2002
Author(s)
William F. Egelhoff Jr., Mark D. Stiles, David P. Pappas, S Alvarado, J Gregg, J Bland, R A. Buhrman, Daniel T. Pierce, J Byers, M Johnson, B Jonker
A recent paper in Science made the claim of 92% polarization for the injection spin polarized electrons from a Ni scanning tunneling microscopy (STM) tip into GaAs(110). Actually they state their result as 92% efficiency for the injection of 100%

Non-collinear spin transfer in Co/Cu/Co multilayers

May 15, 2002
Author(s)
Mark D. Stiles, A Zangwill
We report semi-classical calculations of current polarization, spin accumulation, magnetoresistance, and spin transfer torques in Co/Cu/Co multilayers. A 2 x 2 matrix Boltzman equation is used because the Co layer magnetizations are not necessarily

Spin Polarization of Injected Electrons

May 1, 2002
Author(s)
William F. Egelhoff Jr., Mark D. Stiles, David P. Pappas, Daniel T. Pierce, J M. Byers, J M. Johnson, B T. Jonker, S F. Alvarado, J F. Gregg, J A. Bland, R Buhrman
A recent paper in Science made the claim of 92% polarization for the injection spin polarized electrons from a Ni scanning tunneling microscopy (STM) tip into GaAs(110). Actually they state their result as 92% efficiency for the injection of 100%

Spin-Other-Orbit Interaction and Magnetocrystalline Anisotropy

August 23, 2001
Author(s)
Mark D. Stiles, S Halilov, R Hyman, A Zangwill
We report the effect of the two-body, spin-other-orbit interaction on the magnetocrystalline anisotropy energy of the 3d transition metals. The relevant energy differences were computed for bcc Fe, fcc Ni, and hcp Co using the linearized augmented plane

Surface and Interface Effects in the Growth of Giant Magnetoresistance Spin Valves for Ultrahigh-Density Data-Storage Applications

August 1, 2001
Author(s)
William F. Egelhoff Jr., P J. Chen, Cedric J. Powell, Robert D. McMichael, Mark D. Stiles
The current generation of hard disk drives use Giant Magnetoresistance (GMR) spin valves as the read-head because the GMR effect is currently the most sensitive way to detect magnetic fields at submicron length scales and data rates of {approximately equal

Coercivity in Exchange-Bias Bilayers

January 18, 2001
Author(s)
Mark D. Stiles, Robert D. McMichael
Simulations of magnetic reversal in polycrystalline exchange-bias bilayers exhibit two contributions to the enhanced coercivity found in exchange-bias systems, one due to inhomogeneous reversal and and the other to irreversible transitions in the

Surface and interface effects in the growth of giant magnetoresistance spin valves for ultrahigh-density data-storage applications

January 1, 2001
Author(s)
William F. Egelhoff Jr., P J. Chen, Cedric J. Powell, Robert McMichael, Mark D. Stiles
The current generation of hard disk drives use Giant Magnetoresistance (GMR) spin valves as the read-head because the GMR effect is currently the most sensitive way to detect magnetic fields at submicron length scales and data rates of approximately equal}

The Magnetic Order of Cr in Fe/Cr/Fe(001) Trilayers

January 1, 2001
Author(s)
Daniel T. Pierce, John Unguris, Robert Celotta, Mark D. Stiles
The temperature dependence of the short period oscillatory coupling in Fe/Cr/Fe(001) whisker trilayers, when analyzed in light of recent theory, provides strong evidence that incommensurate spin density wave antiferromagnetic order is induced in the Cr

Gradient Search Method for Orbital-Dependent Density-Functional Calculations

December 15, 2000
Author(s)
R Hyman, Mark D. Stiles, A Zangwill
We describe a gradient search method appropriate for electronic structure problems where the energy functionals are explicitly orbital-dependent. The ground state is found by minimizing the total energy with respect to the scalar and vector potentials that

Exchange Bias Relaxation in CoO-Biased Films

May 1, 2000
Author(s)
Robert McMichael, Chang H. Lee, Mark D. Stiles, F Serpa, P J. Chen, William F. Egelhoff Jr.
Because the memory of the bias direction is carried by the antiferromagnetic order in exchange bias films, the stability of the antiferromagnetic order is critical to the existence of the exchange bias field. Ferromagnetic resonance was used to measure the

Calculation of Spin-Dependent Interface Resistance

January 1, 2000
Author(s)
Mark D. Stiles, David R. Penn
A simple expression for the interface resistance between two materials has been derived by Schep et al. [J. Magn. Magn. Mater. 177, 1166 (1998).] in terms of the transmission probability for electrons at the interface. This approximation is tested for a