Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Spin-Dynamics / Spin-Torque IV

MA 35.8: Vortrag

Donnerstag, 26. März 2009, 17:00–17:15, HSZ 04

Laser-induced quenching of the spin polarization in 3d-ferromagnets studied by time and spin resolved photoemission — •Alexander Weber — Universität Regensburg

In the field of ultrafast magnetization dynamics most progress was achieved by all optical measurements. With optical measurements no direct access to the spin polarization is possible. In order to gain direct insight into the time evolution of the spin polarization after excitation with a fs laser pulse a time and spin-resolved pump probe experiment is applied to measure the quenching of spin polarization in 3d-ferromagnets on a fs timescale. In our experiment the spin polarization of the photoexcited electrons of 8ML Fe/W(110) and 8ML Co/W(110) is measured directly with a Mott-detector. Three different timescales could be distinguished, a fast quenching of spin polarization, a fast remagnetization, and a slow remagnetization. The measured data fit well to a heat-diffusion expanded three temperature model. The fit yields demagnetization times of 0.8 ps and 0.3 ps for Co and Fe, respectively. The qualitative and quantitative accordance to Kerr measurements is discussed.