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Search Publications by: Thomas J. Silva (Fed)

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Displaying 1 - 25 of 135

Symmetry-dependent ultrafast manipulation of nanoscale magnetic domains

December 23, 2022
Nanna Hagstrom, Rahul Jangid, F. N. U. Meera, Diego Turenne, Jeffrey Brock, Erik Lamb, Boyan Stoychev, Justine Schlappa, Natalia Gerasimova, Benjamin Van Kuiken, Rafael Gort, Laurent Mercadier, Loic Le Guyader, Andrey Samartsev, Andreas Scherz, Giuseppe Mercurio, Hermann Durr, Alexander Reid, Monika Arora, Hans Nembach, Justin Shaw, Emmanuelle Jal, Eric Fullerton, Mark Keller, Roopali Kukreja, Stefano Bonetti, Thomas J. Silva, Ezio Iacocca
Symmetry is a powerful concept in physics, but its applicability to far-from-equilibrium states is still being understood. Recent attention has focused on how far-from-equilibrium states lead to spontaneous symmetry breaking. Conversely, ultrafast optical

Ultrafast perturbation of magnetic domains by optical pumping in a ferromagnetic multilayer

October 19, 2022
Dmitriy Zusin, Ezio E. Iacocca, Loic Le Guyader, Alexander H. Reid, William Schlotter, TianMin Liu, Daniel Higley, Giacomo Coslovich, Scott F. Wandel, Phoebe Tengdin, Sheena K. Patel, Anatoly Shabalin, Nelson Hua, Stjepan Hrkac, Hans Nembach, Justin Shaw, Sergio Montoya, Adam Blonsky, Christian Gentry, Mark Hoefer, Margaret M. Murnane, Henry C. Kapteyn, Eric E. Fullerton, Oleg Shpyrko, Hermann Durr, Thomas J. Silva
Ultrafast optical pumping of spatially nonuniform magnetic textures is known to induce far-from-equilibrium spin transport effects. Here, we use ultrafast x-ray diffraction with unprecedented dynamic range to study the laser-induced dynamics of labyrinth

Megahertz-rate Ultrafast X-ray Scattering and Holographic Imaging at the European XFEL

August 23, 2022
Thomas J. Silva, Hans Nembach, Mark Keller, Justin Shaw, Nanna Hagstrom, michael schneider, Nico Kerber, Alexander Yaroslavtsev, Erick Parra, Eric Fullerton, Oleg Shpyrko, Christian Gutt, Hermann Durr, Ezio Iacocca, Roopali Kukreja, stefano Bonetti, Emmanuelle Jal
The advent of X-ray free-electron lasers (XFELs) has revolutionized fundamental science, from atomic to condensed matter physics, from chemistry to biology, giving researchers access to X-rays with unprecedented brightness, coherence, and pulse duration

Comparison of measured and simulated spin-wave mode spectra of magnetic nanostructures

January 6, 2021
Hans Nembach, Robert McMichael, Michael Schneider, Justin Shaw, Thomas J. Silva
Motivated by the importance of magnetization dynamics in nanomagnets for the development and optimization of magnetic devices and sensors, we measured and modeled spin wave spectra in patterned elliptical nanomagnets. Ferromagnetic resonance spectra for

All-optical spin transfer between elemental sublattices in half-metallic Co2MnGe Heusler compound within the femtosecond laser excitation pulse

January 17, 2020
Phoebe Tengdin, Christian Gentry, Adam Blonsky, Dmitriy Zusin, Michael Gerrity, Lukas Hellbruck, Moritz Hofherr, Justin Shaw, Yaroslav Kvashnin, Erna K. Delczeg-Czirjak, Monika Arora, Hans Nembach, Thomas J. Silva, Stefan Mathias, Martin Aeschliman, Henry C. Kapteyn, Danny Thonig, Konstantinos Koumpouras, Olle Eriksson, Margaret M. Murnane
Heusler compounds are exciting materials for future spintronics applications because they display a wide range of tunable electronic and magnetic interactions. Here, we use a femtosecond laser to directly transfer spin polarization from one element to

Ultrafast optically induced spin transfer in ferromagnetic alloys

January 17, 2020
Moritz Hofherr, Soren Hauser, J. K. Dewhurst, Phoebe Tengdin, S Sakshath, Hans Nembach, Tobias Weber, Justin Shaw, Thomas J. Silva, H C. Kapteyn, M Cinchetti, B Rethfeld, M M. Murnane, D Steil, B Stadtmuller, S Sharma, Martin Aeschlimann, S Mathias
The vision of using light to manipulate electronic and spin excitations in materials on their fundamental time and length scales requires new approaches in experiment and theory to observe and understand these excitations. The ultimate speed limit for all

Anomalous spin-orbit torques in magnetic single-layer films

July 22, 2019
Wenrui Wang, Tao Wang, Vivek P. Amin, Yang Wang, Anil Radhakrishna, Angie Davidson, Shane Allen, Thomas J. Silva, Hendrik Ohldag, Davor Balzar, Barry L. Zink, Paul M. Haney, John Xiao, D.G. Cahill, Virginia O. Lorenz, Xin Fan
Spin-orbit interaction (SOI) couples charge and spin transport, enabling electrical control of magnetization, the foundation of next-generation spintronic devices. A quint essential example of SOI-induced transport is the anomalous Hall effect (AHE), first

Near-Unity Spin Hall Ratio in Ni$_x$Cu$_{1-x}$ Alloys

June 7, 2019
Mark W. Keller, Katy Gerace, Monika Arora, Justin M. Shaw, Thomas J. Silva
We report a large spin Hall effect in the 3$d$ transition metal alloy Ni$_x$Cu$_{1-x}$ for $x \in \{ 0.3,0.75\} $, detected via the ferromagnetic resonance of a permalloy (Py = Ni$_{80}$Fe$_{20}$) film deposited in a bilayer with the alloy. A thickness

Spin-current-mediated Rapid Magnon Localisation and Coalescence After Ultrafast Optical Pumping of Ferrimagnetic Alloys

April 15, 2019
Ezio E. Iacocca, TianMin Liu, Alexander H. Reid, Z Fu, S Ruta, P. W. Granitzka, E Jal, S. Bonetti, A. Gray, C E. Graves, R Kukreja, Z Chen, Daniel Higley, T Chase, L L. Guyader, K Hirsch, H Ohldag, W F. Schlotter, G L. Dakovski, Giacomo Coslovich, M C. Hoffmann, S Carron, A Tsukamoto, A Kirilyuk, A V. Kimel, Th Rasing, J Stohr, R F. Evans, T Ostler, R W. Chantrell, M A. Hoefer, Thomas J. Silva, H A. Durr
Sub-picosecond magnetisation manipulation via femtosecond optical pumping has attracted wide attention ever since its original discovery in 1996. However, the spatial evolution of the magnetisation is not yet well understood, in part due to the difficulty

Inhomogeneous magnon scattering during ultrafast demagnetization

October 25, 2018
Ronny J. Knut, Erna Delczeg-Czirjak, Somnath Jana, Justin M. Shaw, Hans T. Nembach, Yaroslav Kvashnin, Robert Stefaniuk, Rameez Malik, Patrik Grychtol, Dmitriy Zusin, Christian Gentry, Raghuveer Chimata, Manuel Pereiro, Johan Soderstrom, Emrah Turgut, Martina Ahlberg, Johan Akerman, H C. Kapteyn, Margaret M. Murnane, Dario A. Arena, Olle Eriksson, Olof Karis, Thomas J. Silva
Ni 0.8Fe 0.2 (Py) and Py alloyed with Cu exhibit intriguing ultrafast demagnetization behavior, where the Ni magnetic moment shows a delayed response relative to the Fe, an effect which is strongly enhanced by Cu alloying. We have studied a broad range of

Localization of Fe d-states in Ni-Fe-Cu alloys and implications for ultrafast demagnetization

October 20, 2018
Ronny J. Knut, Erna Delczeg, Justin Shaw, Hans Nembach, Patrik Grychtol, Dmitriy Zusin, Christian Gentry, Emrah Turgut, Henry C. Kapteyn, Margaret M. Murnane, Dario A. Arena, Olle Eriksson, Olof Karis, Thomas J. Silva
Ni 80Fe 20 (Py) and Py-Cu exhibit intriguing ultrafast demagnetization behavior, where the Ni magnetic moment shows a delayed response relative to the Fe [S. Mathias et al., PNAS \bf 109}, 4792 (2012)]. To unravel the mechanism responsible for this

Magnetic properties in ultra-thin 3d transition metal alloys II: experimental verification of quantitative theories of damping and spin-

April 7, 2018
Martin A. Schoen, Juriaan Lucassen, Hans T. Nembach, Thomas J. Silva, Bert Koopmans, Christian Back, Justin M. Shaw
A systematic study of the Gilbert damping is performed via ferromagnetic resonance for the disordered crystalline binary 3d transition metal alloys NiCo, NiFe and CoFe over the whole range of alloy compositions. After accounting for the inhomogeneous

Magnetic properties of ultra-thin 3d transition metal alloys I: spin and orbital moments and confirmation of Slater-Pauling theory

April 7, 2018
Martin A. Schoen, Juriaan Lucassen, Hans T. Nembach, Thomas J. Silva, Bert Koopmans, Christian Back, Justin M. Shaw
The structure and static magnetic properties - saturation magnetization, perpendicular anisotropy, Landé g-factor, and orbital magnetization - of thin film 3d transition metal alloys are determined over the full range of alloy compositions, via X-ray

Determination of spin Hall effect and spin diffusion length of Pt from self-consistent fitting of damping enhancement and inverse spin-orbit torque measurements

March 22, 2018
Andy Berger, Eric R. Edwards, Hans T. Nembach, Olof Karis, Mathias Weiler, Thomas J. Silva
Understanding the evolution of spin-orbit torque (SOT) with increasing heavy-metal thickness in ferromagnet/normal metal (FM/NM) bilayers is critical for the development of magnetic memory based on SOT. However, several experiments have revealed an

Magnetic damping in sputtered Co2MnGe Heusler compounds with A2, B2 and L21 order: Experiment and Theory

March 19, 2018
Justin M. Shaw, Eric R. Edwards, Martin A. Schoen, Michael L. Schneider, Matthew R. Pufall, Thomas J. Silva, Hans T. Nembach, Erna Delczeg
We show that very low values of the magnetic damping parameter can be achieved in sputter deposited poly-crystalline films of Co2MnGe annealed at relatively low temperatures ranging from 240 oC to 400 oC. Damping values as low as 0.0014 are achieved with

Inductive detection of fieldlike and dampinglike ac inverse spin-orbit torques in ferromagnet/normal-metal bilayers

March 15, 2018
Andy Berger, Eric R. Edwards, Hans T. Nembach, Justin M. Shaw, Alexy D. Karenowska, Mathias Weiler, Thomas J. Silva
Phenomena that result from strong spin-orbit coupling (SOC) at ferromagnet/normal metal (FM/NM) interfaces hold great promise for the development of efficient and scalable spintronic devices. SOC drives non-equilibrium spin-charge conversion, manifest as

Observation of spin-orbit effects with spin rotation symmetry

October 13, 2017
Alisha Humphries, Tao Wang, Eric R. Edwards, Shane Allen, Justin Shaw, Hans Nembach, John Xiao, Thomas J. Silva
The spin-orbit interaction in a nonmagnetic/magnetic multilayer has been intensively studied due to its efficient conversion between a spin current and a charge current. In the spin Hall/Rashba-Edelstein effects (SHE/REE) and inverse spin Hall/Rashba

Stoner vs. Heisenberg: Ultrafast exchange reduction and magnon generation during laser-induced demagnetization

December 28, 2016
Thomas J. Silva, Hans T. Nembach, Justin M. Shaw, Emrah Turgut, Dmitriy Zusin, Dominik Legut, Karel Carva, Ronny Knut, Cong Chen, Zhensheng Tao, Stefan Mathias, Martin Aeschlimann, Peter Oppeneer, Henry Kapteyn, Margaret Murnane, Patrik Grychtol
Understanding how the electronic band structure of a ferromagnetic material is modified during laser-induced demagnetization on femtosecond timescales has been a long-standing question in condensed matter physics. Here, we use ultrafast high harmonics to

Anomalously low magnetic damping of a metallic ferromagnet

May 16, 2016
Justin M. Shaw, Martin Schoen, Danny Thonig, Michael L. Schneider, Thomas J. Silva, Hans T. Nembach, Olle Eriksson, Olof Karis
The phenomenology of magnetic damping is of critical importance to devices which seek to exploit the electronic spin degree of freedom since damping strongly affects the energy required and speed at which a device can operate. However, theory has struggled