Regensburg 1998 – wissenschaftliches Programm

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AM: Magnetismus

AM 8: Elektronentheorie und Modelle geordneter Spinstrukturen

AM 8.3: Vortrag

Dienstag, 24. März 1998, 10:45–11:00, H23

Theory of femtosecond spin dynamics in ferromagnet nickel: Extrinsic properties — •G. P. Zhang and W. Hübner — Max-Planck Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle/Saale

Starting from a many-body Hamiltonian, which includes the on-site correlations between different orbitals and spin-orbit coupling, we study the spin dynamics in Ni by an exact diagonalization method. In this report we focus on those extrinsic parameters, namely, (i) the photon frequencies for the pump and probe pulses, (ii) different optical techniques such as pump-probe spectroscopy of reflectivity and magneto-optics, SHG, or two-photon photoemission (TPPE), (iii) flux of the pulse, (iv) laser spectral width, and (v) optical pulse duration. We will show that laser-pulse duration and spectral width can slow down the observed dynamics considerably. The reduction of the pulse width from 20 eV to 0.2 will prolong the relaxation time to 100 fs. This provides a good opportunity to actively control the spin dynamics rather than passively follow it. This is very meaningful for real applications.