The Experts below are selected from a list of 20550 Experts worldwide ranked by ideXlab platform

S Mangin - One of the best experts on this subject based on the ideXlab platform.

  • signature of Magnetization Dynamics in spin transfer driven nanopillars with tilted easy axis
    Applied Physics Letters, 2013
    Co-Authors: S Mangin, Hong Zhang, Zongzhi Zhang
    Abstract:

    Special spin-transfer-driven magnetic behaviors can take place in a spin valve nanopillar with perpendicular anisotropy due to reduced symmetry of easy axis. Micromagnetic simulation demonstrates a dip in the average Magnetization curve, which corresponds to the experimentally observed undulation of dc resistance. The dip is a signature of spin-transfer-driven reversable magnetic process with slightly tilted easy axis in the free layer. This featured Magnetization Dynamics includes non-uniform Magnetization precession and multi-mode propagating spin waves, which are attributed to the competition among tilted magnetic anisotropy, magnetic field, and spin transfer torque.

  • magnetic susceptibility measurements as a probe of spin transfer driven Magnetization Dynamics
    Applied Physics Letters, 2010
    Co-Authors: Weiwei Lin, Eric E. Fullerton, Christel Berthelot, J Cucchiara, Thomas Hauet, Y Henry, J A Katine, S Mangin
    Abstract:

    An experimental technique has been developed to characterize spin-transfer driven Magnetization Dynamics. It was tested on a nanopillar spin valve with perpendicular anisotropy by measuring the nanopillar voltage under ac injected current (dV/dI), and ac magnetic field (dV/dH). Both the amplitude and the sign of the signals are different which reveals the different influences of the current and the field on the Magnetization Dynamics. Comparison between experiments and macrospin simulation shows that dV/dH measurements reveal the presence of a “canted state” demonstrating that dV/dH and dV/dI measurements are complementary techniques to probe magnetic states and their Dynamics.

  • Magnetic susceptibility measurements as a probe of spin transfer driven Magnetization Dynamics
    Applied Physics Letters, 2010
    Co-Authors: Weiwei Lin, Eric E. Fullerton, Christel Berthelot, J Cucchiara, Thomas Hauet, Y Henry, J A Katine, S Mangin
    Abstract:

    An experimental technique has been developed to characterize spin-transfer driven Magnetization Dynamics. It was tested on a nanopillar spin valve with perpendicular anisotropy by measuring the nanopillar voltage under ac injected current ͑dV / dI͒, and ac magnetic field ͑dV / dH͒. Both the amplitude and the sign of the signals are different which reveals the different influences of the current and the field on the Magnetization Dynamics. Comparison between experiments and macrospin simulation shows that dV / dH measurements reveal the presence of a " canted state " demonstrating that dV / dH and dV / dI measurements are complementary techniques to probe magnetic states and their Dynamics. It is now well established that Magnetization switching or precession can be induced by spin polarized injected current due to the spin transfer torque ͑STT͒ effect. 1,2 This topic has been extensively studied because of the interesting physics and the potential applications for spin transfer magnetic random access memories and high-frequency oscillators.

Hong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • signature of Magnetization Dynamics in spin transfer driven nanopillars with tilted easy axis
    Applied Physics Letters, 2013
    Co-Authors: S Mangin, Hong Zhang, Zongzhi Zhang
    Abstract:

    Special spin-transfer-driven magnetic behaviors can take place in a spin valve nanopillar with perpendicular anisotropy due to reduced symmetry of easy axis. Micromagnetic simulation demonstrates a dip in the average Magnetization curve, which corresponds to the experimentally observed undulation of dc resistance. The dip is a signature of spin-transfer-driven reversable magnetic process with slightly tilted easy axis in the free layer. This featured Magnetization Dynamics includes non-uniform Magnetization precession and multi-mode propagating spin waves, which are attributed to the competition among tilted magnetic anisotropy, magnetic field, and spin transfer torque.

  • Signature of Magnetization Dynamics in spin-transfer-driven nanopillars with tilted easy axis
    Applied Physics Letters, 2013
    Co-Authors: Hong Zhang, Stephane Mangin, Weiwei Lin, Zongzhi Zhang, Yaowen Liu
    Abstract:

    Special spin-transfer-driven magnetic behaviors can take place in a spin valve nanopillar with perpendicular anisotropy due to reduced symmetry of easy axis. Micromagnetic simulation demonstrates a dip in the average Magnetization curve, which corresponds to the experimentally observed undulation of dc resistance. The dip is a signature of spin-transfer-driven reversable magnetic process with slightly tilted easy axis in the free layer. This featured Magnetization Dynamics includes non-uniform Magnetization precession and multi-mode propagating spin waves, which are attributed to the competition among tilted magnetic anisotropy, magnetic field, and spin transfer torque. (C) 2013 American Institute of Physics.

Yaroslav Tserkovnyak - One of the best experts on this subject based on the ideXlab platform.

  • thin film Magnetization Dynamics on the surface of a topological insulator
    Physical Review Letters, 2012
    Co-Authors: Yaroslav Tserkovnyak, Daniel Loss
    Abstract:

    We theoretically study the Magnetization Dynamics of a thin ferromagnetic film exchange coupled with a surface of a strong three-dimensional topological insulator. We focus on the role of electronic zero modes imprinted by domain walls (DWs) or other topological textures in the magnetic film. Thermodynamically reciprocal hydrodynamic equations of motion are derived for the DW responding to electronic spin torques, on the one hand, and fictitious electromotive forces in the electronic chiral mode fomented by the DW, on the other. An experimental realization illustrating this physics is proposed based on a ferromagnetic strip, which cuts the topological insulator surface into two gapless regions. In the presence of a ferromagnetic DW, a chiral mode transverse to the magnetic strip acts as a dissipative interconnect, which is itself a dynamic object that controls (and, inversely, responds to) the Magnetization Dynamics.

  • hydrodynamic theory of coupled current and Magnetization Dynamics in spin textured ferromagnets
    Physical Review B, 2009
    Co-Authors: Clement H Wong, Yaroslav Tserkovnyak
    Abstract:

    We develop the hydrodynamical theory of collinear spin currents coupled to Magnetization Dynamics in metallic ferromagnets. The collective spin density couples to the spin current through a U(1) Berry-phase gauge field determined by the local texture and Dynamics of the Magnetization. We determine phenomenologically the dissipative corrections to the equation of motion for the electronic current, which consist of a dissipative spin-motive force generated by Magnetization Dynamics and a magnetic texture-dependent resistivity tensor. The reciprocal dissipative, adiabatic spin torque on the magnetic texture follows from the Onsager principle. We investigate the effects of thermal fluctuations and find that electronic Dynamics contribute to a nonlocal Gilbert damping tensor in the Landau-Lifshitz-Gilbert equation for the Magnetization. Several simple examples, including magnetic vortices, helices, and spirals, are analyzed in detail to demonstrate general principles.

  • theory of current driven Magnetization Dynamics in inhomogeneous ferromagnets
    ChemInform, 2008
    Co-Authors: Yaroslav Tserkovnyak, Arne Brataas, G Bauer
    Abstract:

    Abstract We give a brief account of recent developments in the theoretical understanding of the interaction between electric currents and inhomogeneous ferromagnetic order parameters. We start by discussing the physical origin of the spin torques responsible for this interaction and construct a phenomenological description. We then consider the electric current-induced ferromagnetic instability and domain-wall motion. Finally, we present a microscopic justification of the phenomenological description of current-driven Magnetization Dynamics, with particular emphasis on the dissipative terms, the so-called Gilbert damping α and the β component of the adiabatic current-driven torque.

  • current induced Magnetization Dynamics in disordered itinerant ferromagnets
    Physical Review B, 2006
    Co-Authors: Yaroslav Tserkovnyak, Arne Brataas, Hans Joakim Skadsem, G Bauer
    Abstract:

    Current-driven Magnetization Dynamics in ferromagnetic metals is studied in a self-consistent adiabatic local-density approximation in the presence of spin-conserving and spin-dephasing impurity scattering. Based on a quantum kinetic equation, we derive Gilbert damping and spin-transfer torques entering the Landau-Lifshitz equation to linear order in frequency and wave vector. Gilbert damping and a current-driven dissipative torque scale identically and compete, with the result that a steady current-driven domain-wall motion is insensitive to spin dephasing in the limit of weak ferromagnetism. A uniform Magnetization is found to be much more stable against spin torques in the itinerant than in the s-d model for ferromagnetism. A dynamic spin-transfer torque reminiscent of the spin pumping in multilayers is identified and shown to govern the current-induced domain-wall distortion.

  • nonlocal Magnetization Dynamics in ferromagnetic heterostructures
    Reviews of Modern Physics, 2005
    Co-Authors: Yaroslav Tserkovnyak, Arne Brataas, G Bauer, Bertrand I Halperin
    Abstract:

    Two complementary effects modify the GHz Magnetization Dynamics of nanoscale heterostructures of ferromagnetic and normal materials relative to those of the isolated magnetic constituents. On the one hand, a time-dependent ferromagnetic Magnetization pumps a spin angular-momentum flow into adjacent materials and, on the other hand, spin angular momentum is transferred between ferromagnets by an applied bias, causing mutual torques on the Magnetizations. These phenomena are manifestly nonlocal: they are governed by the entire spin-coherent region that is limited in size by spin-flip relaxation processes. This review presents recent progress in understanding the Magnetization Dynamics in ferromagnetic heterostructures from first principles, focusing on the role of spin pumping in layered structures. The main body of the theory is semiclassical and based on a mean-field Stoner or spin-density-functional picture, but quantum-size effects and the role of electron-electron correlations are also discussed. A growing number of experiments support the theoretical predictions. The formalism should be useful for understanding the physics and for engineering the characteristics of small devices such as magnetic random-access memory elements.

Weiwei Lin - One of the best experts on this subject based on the ideXlab platform.

  • Signature of Magnetization Dynamics in spin-transfer-driven nanopillars with tilted easy axis
    Applied Physics Letters, 2013
    Co-Authors: Hong Zhang, Stephane Mangin, Weiwei Lin, Zongzhi Zhang, Yaowen Liu
    Abstract:

    Special spin-transfer-driven magnetic behaviors can take place in a spin valve nanopillar with perpendicular anisotropy due to reduced symmetry of easy axis. Micromagnetic simulation demonstrates a dip in the average Magnetization curve, which corresponds to the experimentally observed undulation of dc resistance. The dip is a signature of spin-transfer-driven reversable magnetic process with slightly tilted easy axis in the free layer. This featured Magnetization Dynamics includes non-uniform Magnetization precession and multi-mode propagating spin waves, which are attributed to the competition among tilted magnetic anisotropy, magnetic field, and spin transfer torque. (C) 2013 American Institute of Physics.

  • magnetic susceptibility measurements as a probe of spin transfer driven Magnetization Dynamics
    Applied Physics Letters, 2010
    Co-Authors: Weiwei Lin, Eric E. Fullerton, Christel Berthelot, J Cucchiara, Thomas Hauet, Y Henry, J A Katine, S Mangin
    Abstract:

    An experimental technique has been developed to characterize spin-transfer driven Magnetization Dynamics. It was tested on a nanopillar spin valve with perpendicular anisotropy by measuring the nanopillar voltage under ac injected current (dV/dI), and ac magnetic field (dV/dH). Both the amplitude and the sign of the signals are different which reveals the different influences of the current and the field on the Magnetization Dynamics. Comparison between experiments and macrospin simulation shows that dV/dH measurements reveal the presence of a “canted state” demonstrating that dV/dH and dV/dI measurements are complementary techniques to probe magnetic states and their Dynamics.

  • Magnetic susceptibility measurements as a probe of spin transfer driven Magnetization Dynamics
    Applied Physics Letters, 2010
    Co-Authors: Weiwei Lin, Eric E. Fullerton, Christel Berthelot, J Cucchiara, Thomas Hauet, Y Henry, J A Katine, S Mangin
    Abstract:

    An experimental technique has been developed to characterize spin-transfer driven Magnetization Dynamics. It was tested on a nanopillar spin valve with perpendicular anisotropy by measuring the nanopillar voltage under ac injected current ͑dV / dI͒, and ac magnetic field ͑dV / dH͒. Both the amplitude and the sign of the signals are different which reveals the different influences of the current and the field on the Magnetization Dynamics. Comparison between experiments and macrospin simulation shows that dV / dH measurements reveal the presence of a " canted state " demonstrating that dV / dH and dV / dI measurements are complementary techniques to probe magnetic states and their Dynamics. It is now well established that Magnetization switching or precession can be induced by spin polarized injected current due to the spin transfer torque ͑STT͒ effect. 1,2 This topic has been extensively studied because of the interesting physics and the potential applications for spin transfer magnetic random access memories and high-frequency oscillators.

C. P. Hauri - One of the best experts on this subject based on the ideXlab platform.

  • Off-resonant Magnetization Dynamics phase-locked to an intense phase-stable terahertz transient
    Nature Photonics, 2013
    Co-Authors: C. Vicario, C. Ruchert, F. Ardana-lamas, P. M. Derlet, B. Tudu, J. Luning, C. P. Hauri
    Abstract:

    Off-resonant femtosecond Magnetization Dynamics are observed after applying an ultra-intense, phase-stable terahertz laser field to ferromagnetic cobalt films. The laser's phase and field-strength characteristics are directly imprinted onto the Magnetization response. The off-resonant Magnetization removes the speed limitation caused by the cooling process, providing new opportunities for ultrafast data storage. Controlling Magnetization Dynamics with a femtosecond laser is attracting interest both in fundamental science and in industry because of the potential to achieve magnetic switching at ever faster speeds. Here, we report a coherent, phase-locked coupling between a high-field single-cycle terahertz transient and the Magnetization of ferromagnetic cobalt films. The visualized Magnetization Dynamics follow the temporal terahertz field oscillation, are tightly locked to the terahertz phase and are induced in the absence of resonant excitations and energy deposition. The magnetic response occurs on the timescale of the stimulus and is thus two orders of magnitude faster than the Larmor precession response. The experimental results are excellently reproduced by the Landau–Lifshift–Gilbert semi-empirical model, indicating its applicability to ultrafast Magnetization Dynamics and also demonstrating the marginal effect of the co-propagating terahertz electric field. This novel phenomenon of phase-locked control of Magnetization with a strong terahertz field suggests new opportunities for ultrafast data storage.

  • off resonant Magnetization Dynamics phase locked to an intense phase stable terahertz transient
    Nature Photonics, 2013
    Co-Authors: C. Vicario, C. Ruchert, P. M. Derlet, B. Tudu, J. Luning, C. P. Hauri, F Ardanalamas
    Abstract:

    Off-resonant femtosecond Magnetization Dynamics are observed after applying an ultra-intense, phase-stable terahertz laser field to ferromagnetic cobalt films. The laser's phase and field-strength characteristics are directly imprinted onto the Magnetization response. The off-resonant Magnetization removes the speed limitation caused by the cooling process, providing new opportunities for ultrafast data storage.