The Experts below are selected from a list of 102849 Experts worldwide ranked by ideXlab platform
Jean-yves Bigot - One of the best experts on this subject based on the ideXlab platform.
-
Ultrafast Spin Dynamics in ferromagnetic nickel
Physical Review Letters, 1996Co-Authors: Emmanuel Beaurepaire, J. C. Merle, A. Daunois, Jean-yves BigotAbstract:The relaxation processes of electrons and Spins systems following the absorption of femtosecond optical pulses in ferromagnetic nickel have been studied using optical and magneto-optical pump-probe techniques. The magnetization of the film drops rapidly during the first picosecond, but different electron and Spin Dynamics are observed for delays in the range 0–5 ps. The experimental results are adequately described by a model including three interacting reservoirs (electron, Spin, and lattice).
-
Spin Dynamics in Ferromagnetic Nickel Films
Springer Series in Chemical Physics, 1996Co-Authors: Jean-yves Bigot, A. Daunois, Emmanuel Beaurepaire, J. C. MerleAbstract:The Spin Dynamics in nickel films is studied with femtosecond magneto-optical pump-probe techniques. The onset of an ultrafast demagnetization is observed as the Spin temperature, induced by femtosecond optical pulses, raises close to the Curie point T C .
G. P. Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Femtosecond Spin Dynamics in the time domain
Journal of Applied Physics, 1999Co-Authors: G. P. Zhang, W. HubnerAbstract:Recently magnetization Dynamics on the time scale of 100 fs has been observed. In this article, we explain this ultrafast Spin Dynamics by a microscopic many-body theory. Our theory yields a speed limit of the order of 10 fs for the Spin Dynamics in Ni. The fundamental mechanism is the dephasing of the initial excited states. We investigate the dephasing effects in detail as a function of the number of electronic states and K points. We also calculate the density of states as a crosscheck of our theory, where the typical satellite structure of nickel is present. Moreover, the magnetic moment of the monolayer is found to be 0.88μB, which is also consistent with the experimental results. Finally, based on our Hamiltonian, we briefly discuss the origin of ferromagnetism in our model.
-
Femtosecond electron and Spin Dynamics probed by nonlinear optics
Applied Physics B: Lasers and Optics, 1999Co-Authors: G. P. Zhang, W. HubnerAbstract:A theoretical calculation is performed for the ultrafast Spin Dynamics in nickel using an exact diagonalization method. The present theory mainly focuses on a situation where the intrinsic charge and Spin Dynamics is probed by the nonlinear (magneto-)optical responses on the femtosecond time scale, i.e. optical second harmonic generation (SHG) and the nonlinear magneto-optical Kerr effect (NOLIMOKE). It is found that the ultrafast charge and Spin Dynamics are observable on the time scale of 10 fs. The charge Dynamics proceeds ahead of the Spin Dynamics, which indicates the existence of a Spin memory time. The fast decay results from the loss of coherence in the initial excited state. Both the material specific and experimental parameters affect the Dynamics. We find that the increase of exchange interaction mainly accelerates the Spin Dynamics rather than the charge Dynamics. A reduction of the hopping integrals, such as present at interfaces, slows down the Spin Dynamics significantly. Besides, it is found that a spectrally broad excitation yields the intrinsic speed limit of the charge (SHG) and Spin Dynamics (NOLIMOKE) while a narrower width prolongs the Dynamics. This magnetic interface Dynamics then should become accessible to state of art time resolved nonlinear-optical experiments.
-
Femtosecond Spin Dynamics probed by linear and nonlinear magneto-optics
Journal of Magnetism and Magnetic Materials, 1998Co-Authors: W. Hubner, G. P. ZhangAbstract:Abstract A theoretical study is performed on ultrafast Spin Dynamics as probed by linear and nonlinear (magneto-)optics, such as second harmonic generation (SHG). Both intrinsic Spin and charge Dynamics occur on a time scale of 10 fs. A clear delay of Spin Dynamics with respect to charge Dynamics is observed. Such delay is clear not only for the linear response, but also for the nonlinear response such as χ (2) . We find that the different pump pulse shape could result in a different dynamical process. And for a larger probe frequency, the oscillatory behavior of the Spin Dynamics is clearer, the period is shorter, and the decay time is longer. All of these effects show that one can actively tune the Dynamics by properly choosing the experimental conditions. Our study provides some insights into ultrafast Spin Dynamics.
-
ULTRAFAST Spin Dynamics IN NICKEL
Physical Review B, 1998Co-Authors: W. Hubner, G. P. ZhangAbstract:The Spin Dynamics in Ni is studied by an exact diagonalization method on the ultrafast time scale. It is shown that the femtosecond relaxation of the magneto-optical response results from exchange interaction and Spin-orbit coupling. Each of the two mechanisms affects the relaxation process differently. We find that the intrinsic Spin Dynamics occurs during about 10 fs while extrinsic effects such as laser-pulse duration and spectral width can slow down the observed Dynamics considerably. Thus, our theory indicates that there is still room to accelerate the Spin Dynamics in experiments.
Emmanuel Beaurepaire - One of the best experts on this subject based on the ideXlab platform.
-
Ultrafast Spin Dynamics in ferromagnetic nickel
Physical Review Letters, 1996Co-Authors: Emmanuel Beaurepaire, J. C. Merle, A. Daunois, Jean-yves BigotAbstract:The relaxation processes of electrons and Spins systems following the absorption of femtosecond optical pulses in ferromagnetic nickel have been studied using optical and magneto-optical pump-probe techniques. The magnetization of the film drops rapidly during the first picosecond, but different electron and Spin Dynamics are observed for delays in the range 0–5 ps. The experimental results are adequately described by a model including three interacting reservoirs (electron, Spin, and lattice).
-
Spin Dynamics in Ferromagnetic Nickel Films
Springer Series in Chemical Physics, 1996Co-Authors: Jean-yves Bigot, A. Daunois, Emmanuel Beaurepaire, J. C. MerleAbstract:The Spin Dynamics in nickel films is studied with femtosecond magneto-optical pump-probe techniques. The onset of an ultrafast demagnetization is observed as the Spin temperature, induced by femtosecond optical pulses, raises close to the Curie point T C .
W. Hubner - One of the best experts on this subject based on the ideXlab platform.
-
Femtosecond Spin Dynamics in the time domain
Journal of Applied Physics, 1999Co-Authors: G. P. Zhang, W. HubnerAbstract:Recently magnetization Dynamics on the time scale of 100 fs has been observed. In this article, we explain this ultrafast Spin Dynamics by a microscopic many-body theory. Our theory yields a speed limit of the order of 10 fs for the Spin Dynamics in Ni. The fundamental mechanism is the dephasing of the initial excited states. We investigate the dephasing effects in detail as a function of the number of electronic states and K points. We also calculate the density of states as a crosscheck of our theory, where the typical satellite structure of nickel is present. Moreover, the magnetic moment of the monolayer is found to be 0.88μB, which is also consistent with the experimental results. Finally, based on our Hamiltonian, we briefly discuss the origin of ferromagnetism in our model.
-
Femtosecond electron and Spin Dynamics probed by nonlinear optics
Applied Physics B: Lasers and Optics, 1999Co-Authors: G. P. Zhang, W. HubnerAbstract:A theoretical calculation is performed for the ultrafast Spin Dynamics in nickel using an exact diagonalization method. The present theory mainly focuses on a situation where the intrinsic charge and Spin Dynamics is probed by the nonlinear (magneto-)optical responses on the femtosecond time scale, i.e. optical second harmonic generation (SHG) and the nonlinear magneto-optical Kerr effect (NOLIMOKE). It is found that the ultrafast charge and Spin Dynamics are observable on the time scale of 10 fs. The charge Dynamics proceeds ahead of the Spin Dynamics, which indicates the existence of a Spin memory time. The fast decay results from the loss of coherence in the initial excited state. Both the material specific and experimental parameters affect the Dynamics. We find that the increase of exchange interaction mainly accelerates the Spin Dynamics rather than the charge Dynamics. A reduction of the hopping integrals, such as present at interfaces, slows down the Spin Dynamics significantly. Besides, it is found that a spectrally broad excitation yields the intrinsic speed limit of the charge (SHG) and Spin Dynamics (NOLIMOKE) while a narrower width prolongs the Dynamics. This magnetic interface Dynamics then should become accessible to state of art time resolved nonlinear-optical experiments.
-
Femtosecond Spin Dynamics probed by linear and nonlinear magneto-optics
Journal of Magnetism and Magnetic Materials, 1998Co-Authors: W. Hubner, G. P. ZhangAbstract:Abstract A theoretical study is performed on ultrafast Spin Dynamics as probed by linear and nonlinear (magneto-)optics, such as second harmonic generation (SHG). Both intrinsic Spin and charge Dynamics occur on a time scale of 10 fs. A clear delay of Spin Dynamics with respect to charge Dynamics is observed. Such delay is clear not only for the linear response, but also for the nonlinear response such as χ (2) . We find that the different pump pulse shape could result in a different dynamical process. And for a larger probe frequency, the oscillatory behavior of the Spin Dynamics is clearer, the period is shorter, and the decay time is longer. All of these effects show that one can actively tune the Dynamics by properly choosing the experimental conditions. Our study provides some insights into ultrafast Spin Dynamics.
-
ULTRAFAST Spin Dynamics IN NICKEL
Physical Review B, 1998Co-Authors: W. Hubner, G. P. ZhangAbstract:The Spin Dynamics in Ni is studied by an exact diagonalization method on the ultrafast time scale. It is shown that the femtosecond relaxation of the magneto-optical response results from exchange interaction and Spin-orbit coupling. Each of the two mechanisms affects the relaxation process differently. We find that the intrinsic Spin Dynamics occurs during about 10 fs while extrinsic effects such as laser-pulse duration and spectral width can slow down the observed Dynamics considerably. Thus, our theory indicates that there is still room to accelerate the Spin Dynamics in experiments.
A. Daunois - One of the best experts on this subject based on the ideXlab platform.
-
Ultrafast Spin Dynamics in ferromagnetic nickel
Physical Review Letters, 1996Co-Authors: Emmanuel Beaurepaire, J. C. Merle, A. Daunois, Jean-yves BigotAbstract:The relaxation processes of electrons and Spins systems following the absorption of femtosecond optical pulses in ferromagnetic nickel have been studied using optical and magneto-optical pump-probe techniques. The magnetization of the film drops rapidly during the first picosecond, but different electron and Spin Dynamics are observed for delays in the range 0–5 ps. The experimental results are adequately described by a model including three interacting reservoirs (electron, Spin, and lattice).
-
Spin Dynamics in Ferromagnetic Nickel Films
Springer Series in Chemical Physics, 1996Co-Authors: Jean-yves Bigot, A. Daunois, Emmanuel Beaurepaire, J. C. MerleAbstract:The Spin Dynamics in nickel films is studied with femtosecond magneto-optical pump-probe techniques. The onset of an ultrafast demagnetization is observed as the Spin temperature, induced by femtosecond optical pulses, raises close to the Curie point T C .
