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Search Publications by: Stephen E. Russek (Fed)

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Displaying 76 - 100 of 170

Injection Locking and Phase Control of Spin Transfer Nano-Oscillators

August 5, 2005
Author(s)
William Rippard, Matthew Pufall, Shehzaad F. Kaka, Thomas J. Silva, Stephen E. Russek, Jordan A. Katine
We have directly measured phase locking of spin transfer oscillators to an injected ac current. The oscillators lock to signals up to several hundred megahertz away from their natural oscillation frequencies, depending on the relative strength of the input

Low-frequency noise measurements on commercial magnetoresistive magnetic field sensors

May 17, 2005
Author(s)
Nathan Stutzke, Stephen E. Russek, David P. Pappas, Mark Tondra
Low frequency noise was measured in the frequency range from 0.1 Hz to 10 kHz on a variety of commercially available magnetic sensors. The types of sensors investigated include anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR), and tunnel

Advantages of superconducting quantum interference device-detected magnetic resonance over conventional high-frequency electron paramagnetic resonance for characterization of nanomagnetic materials

May 16, 2005
Author(s)
Brant Cage, Stephen E. Russek, David Zipse, Naresh S. Dalal
A dc-detected high-frequency electron paramagnetic resonance (HF-EPR) technique, based on a standard superconducting quantum interference device (SQUID) magnetometer, has significant advantages over traditional HF-EPR based on microwave absorption

Finite-temperature modeling of nanoscale spin-transfer oscillators

March 31, 2005
Author(s)
Stephen E. Russek, Shehzaad F. Kaka, William Rippard, Matthew Pufall, Thomas J. Silva
Magnetization dynamics induced by spin-polarized currents in magnetic nanodevices have been numerically simulated using a single-domain model proposed by Slonczewski extended to include temperature effects. For currents with a spin polarization

Frequency modulation of spin-transfer oscillators

February 18, 2005
Author(s)
Matthew Pufall, William Rippard, Shehzaad F. Kaka, Thomas J. Silva, Stephen E. Russek
Spin-polarized dc electric current flowing into a magnetic layer can induce precession of the magnetization at a frequency that depends on current. We show that addition of an ac current to this dc bias current results in a frequency modulated (FM)

Design for a multifrequency high magnetic field superconducting quantum interference device-detected quantitative electron paramagnetic resonance probe: Spin-lattice relaxation of cupric sulfate pentahydrate (CuSO 4 &#82265H 2 O

November 1, 2004
Author(s)
Brant Cage, Stephen E. Russek
We have designed a spectrometer for the quantitative determination of electron paramagnetic resonance (EPR) at high magnetic fields and frequencies. It uses a superconducting quantum interference device (SQUID) for measuring the magnetic moment as a

Micromechanical torque magnetometer with sub-monolayer sensitivity

October 29, 2004
Author(s)
Dong-Hoon Min, Andrew McCallum, Stephen E. Russek, John M. Moreland
We have developed a micromechanical torque sensor with sub-monolayer sensitivity for in situ monitoring of the magnetic moment of thin films during deposition. The film is deposited onto a microcantilever. The torque on the film is determined by measuring

Spin transfer switching of spin valve nanopillars using nanosecond pulsed currents

October 29, 2004
Author(s)
Shehzaad F. Kaka, Matthew Pufall, William Rippard, Thomas J. Silva, Stephen E. Russek, Jordan A. Katine, Matt Carey
Spin valve nanopillars are reversed via the mechanism of spin momentum transfer using current pulses applied perpendicular to the film plane of the device. The applied pulses were varied in amplitude from 1.8 to 7.8 mA, and varied in duration within the

Large-angle, gigahertz-rate random telegraph switching induced by spin-momentum transfer

July 27, 2004
Author(s)
Matthew Pufall, William Rippard, Shehzaad F. Kaka, Stephen E. Russek, Thomas J. Silva, Jordan A. Katine, Matt Carey
We show that a spin-polarized dc current passing through a small magnetic element induces two-state, random telegraph switching of the magnetization via the spin-momentum transfer effect. The resistances of the states differ by up to 50% of the change due

In-situ observation of nano-oxide formation in magnetic thin films

July 4, 2004
Author(s)
Andrew McCallum, Stephen E. Russek
In situ conductance and reflected high energy electron diffraction (RHEED) measurements were taken during the oxidation of 20-nm-thick Co and CoFe layers. The conductance shows an initial drop with exposure to oxygen followed by a period of increasing

Direct-Current Induced Dynamics in Co 90 Fe 10 /Ni 80 Fe 20 Point Contacts

January 16, 2004
Author(s)
William Rippard, Matthew Pufall, Shehzaad F. Kaka, Stephen E. Russek, Thomas J. Silva
We have directly measured coherent high-frequency magnetization dynamics in ferromagnetic films induced by a spin-polarized dc current. The precision frequency can be tuned over a range of several gigahertz by varying the applied current. The frequencies

Polymer-derived SiCN composites with magnetic properties

November 1, 2003
Author(s)
Atanu Saha, Sandeep R. Shah, Rishi Raj, Stephen E. Russek
Composites consisting of particles of α-iron dispersed in silicon carbonitride (SiCN) were fabricated by a polymer route. The composites had iron inclusions with the same magnetization as bulk iron, but they resisted oxidation up to 500°C and had a

High-frequency noise measurements in spin-valve Devices

July 1, 2003
Author(s)
N. A. Stutzke, S. L. Burkett, Stephen E. Russek
High-frequency magnetic noise in magnetoresistive devices being developed for read-sensor and magnetic random access memory applications may present fundamental limitations on the performance of sub-micrometer magnetic devices. High- frequency magnetic

In-situ conductance characterization of Fe/Ag multilayer contacts on GaAs

July 1, 2003
Author(s)
Dustin Hite, Stephen E. Russek, David P. Pappas
Electrical transport characteristics for epitaxially grown Ag/Fe/Ag multilayers on GaAs(100) and GaAs(110) have been studied under various growth conditions. The surfaces and structure of the multilayer were characterized by low energy electron diffraction

High-Frequency Measurements of Spin Valve Films and Devices

May 15, 2003
Author(s)
Shehzaad F. Kaka, John P. Nibarger, Stephen E. Russek, N. A. Stutzke, S. L. Burkett
High-frequency measurements of spin-valve films and devices, made using several different measurement techniques, are presented and compared. Pulsed inductive measurements were made on sheet films and provide insight into the intrinsic dynamical properties

High-speed switching and rotational dynamics in small magnetic thin-film devices

January 1, 2003
Author(s)
Stephen E. Russek, Shehzaad F. Kaka, Robert McMichael, Michael J. Donahue
The intent of this chapter is to review high frequency magnetic device measurements and modeling work at NIST which is being conducted to support the development of high-speed read sensors, magnetic random access memory, and magnetoelectronic applications

Spin-Current Induced Magnetotransport in Co/Cu/Co Nanostructures

September 1, 2002
Author(s)
Fred B. Mancoff, Stephen E. Russek
We report measurements on sub-100 nm current-perpendicular-to-place Co/Cu/Co spin-valves. The giant magnetoresistance versus applied magnetic field shows the switching in individual patterned Co nanomagnets. Spin transfer from the spin-polarized current to