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MA: Magnetismus

MA 18: Spindynamik / Ummagnetisierungsvorg
änge

MA 18.2: Vortrag

Mittwoch, 26. März 2003, 15:30–15:45, HSZ/401

Ultrafast demagnetization in Ni: Theory of magneto-optics for non-equilibrium electron distributions — •Peter M. Oppeneer¹ and Ansgar Liebsch² — ¹IFW Dresden — ²IFF, Forschungszentrum Jülich

The complex conductivity tensor of Ni is evaluated for non-equilibrium electron distributions to investigate the sensitivity of the magneto-optical Kerr effect to electronic thermalization processes in ultra-fast pump-probe experiments. To account for the electronic redistributions generated by the pump laser pulse in the initial stage of electronic thermalization, step-like model distributions below and above the Fermi energy are introduced. In a more detailed description band and spin dependent occupation numbers are computed and employed to mimic the so-called dichroic bleaching effect. Thus, certain optical transitions are blocked while new ones become allowed. Although individual elements of the conductivity tensor are modified substantially, the Kerr rotation and ellipticity vary only slightly as a result of cancellations. A small disproportionation between the Kerr rotation and ellipticity occurs. The dichroic bleaching effect appears thus to be smaller than previously suggested, and the Kerr rotation remains therefore a proper tool to probe the magnetization.