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  • 1
    Electronic Resource
    Electronic Resource
    Ferromagnet–semiconductor device with tunable tunnel characteristics (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6379-6381 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A device is proposed consisting of a GaAs/AlxGa1−xAs heterostructure with a ferromagnetic strip placed on top that has an easy axis of magnetization perpendicular to the underlying two-dimensional electron gas. In addition, the strip is gated to form a combined magnetostatic and electrostatic barrier for the conduction electrons. On the basis of a simple model, which is of the Landauer–Büttiker type, such a structure is shown to have three different regimes of operation. Whereas for a certain regime, electrons can move according to the classical diamagnetic motion, there is also the possibility of tuning the device between nonresonant and resonant tunneling behavior. In the latter case the combined magnetostatic and electrostatic barrier acts as an energy and momentum filter. The proposed device could find application in digital logic circuits as an electromagnetic field-effect transistor. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372712
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  • 2
    Electronic Resource
    Electronic Resource
    Ab initio nonequilibrium calculation of magnetic tunnel junctions (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7561-7563 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a nonequilibrium band-structure calculation of a magnetic tunnel junction using the ab initio screened Korringa–Kohn–Rostoker multiple scattering formalism together with the local spin density approximation. We find that the current is determined by the surface density of states (DOS) and the bias dependence of the barrier in our Fe(100)/vacuum(30 Å)/Fe(100) model junction. The existence of quasilocalized states at the interfaces leads to the effect of negative differential resistance at low bias. For high bias the surface DOS yields an enhanced spin polarization of the current. Therefore, the magnetoresistance ratio becomes strongly quenched since the current is dominated by the minority channel for both the parallel and the antiparallel configuration of the magnetic electrodes. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1357861
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  • 3
    Electronic Resource
    Electronic Resource
    Voltage dependence of the magnetic state in magnetic tunnel junctions (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5221-5223 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In magnetic tunnel junctions (MTJ) we study how the magnetic state depends on the tunnel current. We present data on the I–V dependence of the MTJ in strong biasing fields up to 4 V, and propose that the observed hysteresis may have its origin in spin-polarized electrons influencing locally the magnetic state of the system. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373301
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  • 4
    Electronic Resource
    Electronic Resource
    Nonlinear spin wave resonance modes (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4972-4974 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nonlinear spin wave resonance modes of magnetic films are studied both theoretically and experimentally. In the theoretical analysis the normal modes with arbitrary amplitudes are studied for a film magnetized perpendicular to its plane. The film is assumed to be uniform apart from a layer close to the surfaces, where the spins may be pinned. The spin wave resonance mode of the lowest frequency (principal mode) is considered in detail for the film with arbitrary surface spin pinning. The mode profile changes with increasing amplitude trying to redistribute itself in a more uniform manner across the film thickness. The nonlinear shift of the resonance field depends critically on the pinning. In experiments, we use yttrium–iron–garnet films with a strong gradient in the anisotropy field across the film thickness. With increasing pump power, the principal mode shows a sublinear shift of the resonance field and superlinear growth in the absorption amplitude. These features are explained in terms of the spatial nonuniformity of the mode profile. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373219
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanism for strong nonlinearities in the Faraday rotation and absorption in the ferromagnetic semiconductor CdCr2Se4 (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6472-6474 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: At high laser radiation intensities a strong nonlinear Faraday rotation (FR) may be observed in a relatively narrow energy band near the absorption edge of CdCr2Se4. To study the nature of this effect, we investigated the influence of the incident radiation intensity on the spectral properties of the FR and the circularly polarized light absorption, and studied the dynamics of the observed nonlinearities. As the laser radiation intensity increases, we find a strong growth of the resonance structure at the absorption edge and an enhancement of the FR in the band associated with the resonance. The nonlinear FR is a non-monotonic function of the radiation intensity and reaches a local maximum, which is about twice the value of the rotation angle for the linear effect. The dynamics of the observed nonlinearities show that the nonlinearities are caused by photo-excited charge carriers. These carriers screen the internal electrical fields and lead to a narrowing and growth of the excitonic resonance in the absorption spectra and FR. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372741
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