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Search Publications by: Hans Nembach (Assoc)

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Displaying 51 - 66 of 66

Ultrafast element-specific magnetization dynamics of complex magnetic materials on a table-top

December 21, 2012
Author(s)
Justin M. Shaw, Stefan Mathias, Chan La-O=Vorakiat, Emrah Turgut, Patrik Grychtol, Roman Adam, Dennis Rudolf, Hans T. Nembach, Martin Aeschlimann, Claus Schneider, Henry Kapteyn, Margaret Murnane
We review recent progress in femtosecond magnetization dynamics probed by extreme ultraviolet pulses from high-harmonic generation. In a transversal magneto-optical Kerr geometry, we established an ultrafast, element-specific experimental capability – on a

Ultrafast manetization enhancement in metallic multilayers driven by superdiffusive spin current

September 4, 2012
Author(s)
Thomas J. Silva, Justin M. Shaw, Hans T. Nembach, Dennis Rudolf, Chan La-O-Vorakiat, Marco Battiato, Roman Adam, Emrah Turgut, Stefan Mathias, Margaret M. Murnane, Henry C. Kapteyn, Claus M. Schneider
Uncovering the physical mechanisms that govern ultrafast charge and spin dynamics is crucial for understanding correlated matter as well as the fundamental limits of ultrafast spin-based electronics. Spin dynamics in magnetic materials can be driven by

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

Magneto-optical observation of four-wave scattering in a 15 nm Ni 81 Fe 19 film during large angle magnetization precession

November 14, 2011
Author(s)
Hans T. Nembach, Karen Livesey, Michael Kostylev, Patrica Martin-Pimentel, Sebastian Hermsdoerfer, Britta Leven, Juergen Fassbender, Burkard Hillebrands
Large angle magnetization precession induced by a short pulsed magnetic field in a 15 nm thick Ni 81Fe 19 film is observed using a time-resolved magneto-optical Kerr effect technique with sensitivity to all three components of the magnetization vector. A

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

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

Calibrated Broadband Electrical Characterization of Nanowires

June 8, 2008
Author(s)
Thomas Mitchell (Mitch) Wallis, Atif A. Imtiaz, Hans Nembach, Kristine A. Bertness, Norman Sanford, Paul T. Blanchard, Pavel Kabos
A technique is presented for the broadband electrical characterization of nanowires. The technique relies on established on-wafer calibration methods as well as a direct measurement of the capacitive coupling that is in parallel with the nanowire

Near-field microwave microscope measurements to characterize bulk material properties

June 12, 2007
Author(s)
Atif A. Imtiaz, Thomas Baldwin, Hans T. Nembach, Thomas M. Wallis, Pavel Kabos
We measured bulk dielectric (Fused Silica), semiconductor (Silicon) and metal (Copper), with a Near-field Scanning Microwave Microscope (NSMM). We use three bulk materials to test the existing quasi-static theoretical approach to de-embed the materials

Metrology for High-Frequency Nanoelectronics

March 27, 2007
Author(s)
Thomas Mitchell (Mitch) Wallis, Atif A. Imtiaz, Hans Nembach, Paul Rice, Pavel Kabos
Two metrological tools for high frequency measurements of nanoscale systems are described: (i) tow/N-port analysis of nanoscale devices as well as (ii) near-field scanning microwave microscopy (NSMM) for materials characterization. Calibrated two/N-port