"Ultrafast reduction of the total magnetization in iron "

A. Fognini: T. U. Michlmayr, G. Salvatella, C. Wetli, U. Ramsperger, T. Bähler, F. Sorgenfrei, M. Beye, A. Eschenlohr, N. Pontius, C. Stamm, F. Hieke, M. Dell'Angela, S. de Jong, R. Kukreja, N. Gerasimova, V. Rybnikov, A. Al-Shemmary, H. Redlin, J. Raabe, A. Föhlisch, H. A. Dürr, W. Wurth, D. Pescia, A. Vaterlaus and Y. Acremann; Applied Physics Letters, 01/20/14.

Additional Authors: T. U. Michlmayr, G. Salvatella, C. Wetli, U. Ramsperger, T. Bähler, F. Sorgenfrei, M. Beye, A. Eschenlohr, N. Pontius, C. Stamm, F. Hieke, M. Dell'Angela, S. de Jong, R. Kukreja, N. Gerasimova, V. Rybnikov, A. Al-Shemmary, H. Redlin, J. Raabe, A. Föhlisch, H. A. Dürr, W. Wurth, D. Pescia, A. Vaterlaus and Y. Acremann

Abstract:

Surprisingly, if a ferromagnet is exposed to an ultrafast laser pulse, its apparent magnetization is reduced within less than a picosecond. Up to now, the total magnetization, i.e., the average spin polarization of the whole valence band, was not detectable on a sub-picosecond time scale. Here, we present experimental data, confirming the ultrafast reduction of the total magnetization. Soft x-ray pulses from the free electron laser in Hamburg (FLASH) extract polarized cascade photoelectrons from an iron layer excited by a femtosecond laser pulse. The spin polarization of
the emitted electrons is detected by a Mott spin polarimeter.