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C T Rogers - One of the best experts on this subject based on the ideXlab platform.

  • subnanosecond magnetization dynamics measured by the second harmonic magneto optic kerr effect
    Applied Physics Letters, 1999
    Co-Authors: T M Crawford, Thomas J Silva, Charles W Teplin, C T Rogers
    Abstract:

    We have measured the in-plane magnetization dynamics of Ni81Fe19 films using the surface- and interface-sensitive second-harmonic magneto-optic Kerr effect. The dynamical magnetization was measured on patterned Ni81Fe19 stripes as a function of an in-plane magnetic field applied parallel to the Anisotropy Axis. The excitation sources were 100 ps risetime magnetic field impulses and steps. The minimum magnetization switching times were <300 ps, and precessional free-induction decay was observed. The dynamics for both impulse and step excitation are fitted to the Landau–Lifshitz equation, yielding values for the Anisotropy field, gyroscopic splitting factor, and damping. The local surface precessional frequency and Anisotropy are different from the average bulk values, demonstrating that this technique possesses the necessary sensitivity to detect variations in localized surface and interface dynamics.

  • inductive measurement of ultrafast magnetization dynamics in thin film permalloy
    Journal of Applied Physics, 1999
    Co-Authors: Thomas J Silva, C G Lee, T M Crawford, C T Rogers
    Abstract:

    An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied field pulse oriented in the plane of the film and transverse to the Anisotropy Axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc bias field parallel to the Anisotropy Axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc bias field. Damping for both impulse and step excitations exhibits a strong dependence on bias field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc bias field. Transformation of the data to the frequency domain reveals a higher or...

  • inductive measurement of ultrafast magnetization dynamics in thin film permalloy
    Journal of Applied Physics, 1999
    Co-Authors: Thomas J Silva, C G Lee, T M Crawford, C T Rogers
    Abstract:

    An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied field pulse oriented in the plane of the film and transverse to the Anisotropy Axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc bias field parallel to the Anisotropy Axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc bias field. Damping for both impulse and step excitations exhibits a strong dependence on bias field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc bias field. Transformation of the data to the frequency domain reveals a higher order precessional mode which is also preferentially excited at low dc bias fields. A possible source for both phenomena is precessional mode saturation for large peak rotations. The technique has the potential for 20 ps resolution, although only 120 ps resolution is demonstrated due to the limited bandwidth of the waveguides used.

A Layadi - One of the best experts on this subject based on the ideXlab platform.

  • exchange coupled bilayer thin films with tilted out of plane Anisotropy easy Axis
    Journal of Applied Physics, 2012
    Co-Authors: A Layadi
    Abstract:

    The ferromagnetic resonance (FMR) modes are worked out for the case of exchange coupled bilayer thin films where the Anisotropy Axis in the ferromagnetic film is tilted out of the plane. General formulas are obtained for the mode position, frequency and field linewidths, and intensity for an arbitrary tilt angle. The analysis is then applied for the in-plane, weak and strong perpendicular anisotropies. Analytical expressions for the magnetization curve and the FMR modes are derived. It will be shown how the exchange Anisotropy field HE, the uniaxial Anisotropy HK, and the magnetization angle are related to the FMR spectrum characteristics and how they can be found in a straightforward manner.

  • ferromagnetic resonance modes in single and coupled layers with oblique Anisotropy Axis
    Physical Review B, 2001
    Co-Authors: A Layadi
    Abstract:

    Ferromagnetic resonance (FMR) modes in thin films with oblique Anisotropy Axis are investigated. In such films, the Anisotropy Axis is tilted from the normal with a tilt angle \ensuremath{\delta}. The equivalent magnetic field of such an Anisotropy is derived. The mode position (resonant field) ${H}_{R},$ the linewidth $\ensuremath{\Delta}H,$ and the peak intensity have been calculated. The effect of the tilt angle on these parameters is discussed. The FMR modes of two coupled ferromagnetic thin films with oblique Anisotropy axes have also been studied. Analytical expressions for the resonance condition have been found for strong ferromagnetic and antiferromagnetic coupling.

Thomas J Silva - One of the best experts on this subject based on the ideXlab platform.

  • subnanosecond magnetization dynamics measured by the second harmonic magneto optic kerr effect
    Applied Physics Letters, 1999
    Co-Authors: T M Crawford, Thomas J Silva, Charles W Teplin, C T Rogers
    Abstract:

    We have measured the in-plane magnetization dynamics of Ni81Fe19 films using the surface- and interface-sensitive second-harmonic magneto-optic Kerr effect. The dynamical magnetization was measured on patterned Ni81Fe19 stripes as a function of an in-plane magnetic field applied parallel to the Anisotropy Axis. The excitation sources were 100 ps risetime magnetic field impulses and steps. The minimum magnetization switching times were <300 ps, and precessional free-induction decay was observed. The dynamics for both impulse and step excitation are fitted to the Landau–Lifshitz equation, yielding values for the Anisotropy field, gyroscopic splitting factor, and damping. The local surface precessional frequency and Anisotropy are different from the average bulk values, demonstrating that this technique possesses the necessary sensitivity to detect variations in localized surface and interface dynamics.

  • inductive measurement of ultrafast magnetization dynamics in thin film permalloy
    Journal of Applied Physics, 1999
    Co-Authors: Thomas J Silva, C G Lee, T M Crawford, C T Rogers
    Abstract:

    An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied field pulse oriented in the plane of the film and transverse to the Anisotropy Axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc bias field parallel to the Anisotropy Axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc bias field. Damping for both impulse and step excitations exhibits a strong dependence on bias field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc bias field. Transformation of the data to the frequency domain reveals a higher or...

  • inductive measurement of ultrafast magnetization dynamics in thin film permalloy
    Journal of Applied Physics, 1999
    Co-Authors: Thomas J Silva, C G Lee, T M Crawford, C T Rogers
    Abstract:

    An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied field pulse oriented in the plane of the film and transverse to the Anisotropy Axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc bias field parallel to the Anisotropy Axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc bias field. Damping for both impulse and step excitations exhibits a strong dependence on bias field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc bias field. Transformation of the data to the frequency domain reveals a higher order precessional mode which is also preferentially excited at low dc bias fields. A possible source for both phenomena is precessional mode saturation for large peak rotations. The technique has the potential for 20 ps resolution, although only 120 ps resolution is demonstrated due to the limited bandwidth of the waveguides used.

T M Crawford - One of the best experts on this subject based on the ideXlab platform.

  • subnanosecond magnetization dynamics measured by the second harmonic magneto optic kerr effect
    Applied Physics Letters, 1999
    Co-Authors: T M Crawford, Thomas J Silva, Charles W Teplin, C T Rogers
    Abstract:

    We have measured the in-plane magnetization dynamics of Ni81Fe19 films using the surface- and interface-sensitive second-harmonic magneto-optic Kerr effect. The dynamical magnetization was measured on patterned Ni81Fe19 stripes as a function of an in-plane magnetic field applied parallel to the Anisotropy Axis. The excitation sources were 100 ps risetime magnetic field impulses and steps. The minimum magnetization switching times were <300 ps, and precessional free-induction decay was observed. The dynamics for both impulse and step excitation are fitted to the Landau–Lifshitz equation, yielding values for the Anisotropy field, gyroscopic splitting factor, and damping. The local surface precessional frequency and Anisotropy are different from the average bulk values, demonstrating that this technique possesses the necessary sensitivity to detect variations in localized surface and interface dynamics.

  • inductive measurement of ultrafast magnetization dynamics in thin film permalloy
    Journal of Applied Physics, 1999
    Co-Authors: Thomas J Silva, C G Lee, T M Crawford, C T Rogers
    Abstract:

    An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied field pulse oriented in the plane of the film and transverse to the Anisotropy Axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc bias field parallel to the Anisotropy Axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc bias field. Damping for both impulse and step excitations exhibits a strong dependence on bias field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc bias field. Transformation of the data to the frequency domain reveals a higher or...

  • inductive measurement of ultrafast magnetization dynamics in thin film permalloy
    Journal of Applied Physics, 1999
    Co-Authors: Thomas J Silva, C G Lee, T M Crawford, C T Rogers
    Abstract:

    An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied field pulse oriented in the plane of the film and transverse to the Anisotropy Axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc bias field parallel to the Anisotropy Axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc bias field. Damping for both impulse and step excitations exhibits a strong dependence on bias field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc bias field. Transformation of the data to the frequency domain reveals a higher order precessional mode which is also preferentially excited at low dc bias fields. A possible source for both phenomena is precessional mode saturation for large peak rotations. The technique has the potential for 20 ps resolution, although only 120 ps resolution is demonstrated due to the limited bandwidth of the waveguides used.

W K Theumann - One of the best experts on this subject based on the ideXlab platform.

  • mean field theory of the ising random Anisotropy Axis model in the large component limit
    Physical Review B, 1993
    Co-Authors: David Dominguez, W K Theumann
    Abstract:

    The ising random-Anisotropy-Axis model with additional noncubic Anisotropy is investigated in mean-field theory in the limit p\ensuremath{\rightarrow}\ensuremath{\infty} for p-component random vectors on a lattice of N sites. The effects of Anisotropy for statistically independent and identically distributed random-vector components with a trimodal probability distribution are studied in the limits \ensuremath{\alpha}\ensuremath{\equiv}p/N=0 and \ensuremath{\alpha}g0. Ferromagnetic, mixed, and residual ordered phases are found in the first case, while only mixed ordered and spin-glass phases are found for the latter. Phase diagrams with explicit phase boundaries are obtained.