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Search Publications by: Justin Shaw (Fed)

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Displaying 126 - 150 of 162

Probing the timescale of the exchange interaction in a ferromagnetic alloy

January 27, 2012
Author(s)
Justin M. Shaw, Stefan Mathias, Chan La-O-Vorakiat, Hans T. Nembach, Thomas J. Silva, Mark Siemens, Henry Kapteyn, Margaret Murnane
The underlying physics of all ferromagnetic behavior is the cooperative interaction between individual atomic magnetic moments that results in a macroscopic magnetization. In this work, we use extreme ultraviolet pulses from high-harmonic generation as an

Ultrafast Demagnetization Measurements using Extreme Ultraviolet Light: Comparison of Electronic and Magnetic Contributions

January 23, 2012
Author(s)
Thomas J. Silva, Justin M. Shaw, Hans T. Nembach, Margaret M. Murnane, Henry C. Kapteyn, Chan La-O-Vorakiat, Stefan Mathias, Emrah Turgut, Teale A. Carson, Martin Aeschlimann, Claus M. Schneider
Ultrashort pulses of extreme ultraviolet light from high-harmonic generation are a new tool for probing coupled charge, spin, and phonon dynamics with element specificity, attosecond pump-probe synchronization, and time resolution of a few-femtoseconds in

Perpendicular ferromagnetic resonance measurements of damping and Lande g-factor in sputtered (Co 2 Mn) 1-x Ge x thin films

August 8, 2011
Author(s)
Thomas J. Silva, Hans T. Nembach, Justin M. Shaw, Michael Schneider, Matt Carey, Stefan Maat, Jeff Childress
X-ray diffraction (XRD), magnetometry, and ferromagnetic resonance (FMR) measurements were performed on sputtered thin films of the nominal Heusler alloy (Co 2Mn) 1-xGe x with varying Ge content and annealing temperature. XRD indicates some degree of L2 1

Damping phenomena in Co 90 Fe 10 /Ni multilayers and alloys

July 6, 2011
Author(s)
Justin M. Shaw, Hans T. Nembach, Thomas J. Silva
We used perpendicular ferromagnetic resonance to measure the damping parameter in Co 90Fe 10/Ni multilayers over a wide range of layer thicknesses. The magnetic anisotropy within this range varied from in-pane to out-of-plane. We measured (Co 90Fe 10) xNi

Effects of shape distortions and imperfections on mode frequencies and collective linewidths in nanomagnets

March 28, 2011
Author(s)
Hans T. Nembach, Justin M. Shaw, Thomas J. Silva, Ward L. Johnson, Sudook A. Kim, Robert D. McMichael, Pavel Kabos
We used Brillouin light scattering to show that shape distortions in Ni80Fe20 nanoelements can have a dramatic effect on the measured linewidth of certain modes. By intentionally introducing an amount of “egg-like” shape distortion to an ideal elliptical

Intrinsic defects in perpendicularly magnetized multilayer thin films and nanostructures

October 26, 2010
Author(s)
Justin M. Shaw, Miles Olsen, June W. Lau, Michael L. Schneider, Thomas J. Silva, Olav Hellwig, Elizabeth Dobisz, Bruce D. Terris
Intrinsic magnetic defects in perpendicularly magnetized nanostructures reduce the predictability of device and developing recording technologies. In addition to a distribution of local anisotropy fields, we show that such defects also exhibit variations

Spin-transfer dynamics in spin valves with out-of-plane magnetized CoNi free layers

January 29, 2010
Author(s)
William H. Rippard, Alina M. Deac, Matthew R. Pufall, Justin M. Shaw, Mark W. Keller, Stephen E. Russek, Gerrit E. Bauer, Claudio Serpico
We have measured spin-transfer-induced dynamics in magnetic nanocontact devices having a perpendicularly magnetized Co/Ni free layer and an in-plane magnetized CoFe fixed layer. The frequencies and powers of the excitations agree well with the predictions

Ultrafast Demagnetization Dynamics at the M Edges of Magnetic Elements Observed Using a Tabletop High-Harmonic Soft X-Ray Source

December 15, 2009
Author(s)
Thomas J. Silva, Justin Shaw, Hans Nembach, Chan La-O-Vorakiat, Mark Siemens, Margaret M. Murnane, Henry C. Kapteyn, Stefan Mathias, Martin Aeschlimann, Patrik Grychtol, Roman Adam, Claus M. Schneider
We use few-femtosecond soft x-ray pulses from high-harmonic generation to extract element-specific demagnetization dynamics and hysteresis loops of a compound material for the first time. Using a geometry where high-harmonic beams are reflected from a

Microwave assisted magnetization reversal in single domain nanoelements

July 6, 2009
Author(s)
Hans T. Nembach, Hans Bauer, Justin M. Shaw, Michael Schneider, Thomas J. Silva
We studied the microwave assisted magnetic reversal in 65×71 nm 2 elliptical Ni 80Fe 20 nanomagnets with a thickness of 10 nm. Hysteresis curves were measured by magneto-optical Kerr effect for a range of microwave frequencies and amplitudes. We observe a