Regensburg 2016 – scientific programme

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MA: Fachverband Magnetismus

MA 36: Magnetization and Demagnetization Dynamics III

MA 36.4: Talk

Wednesday, March 9, 2016, 15:45–16:00, H34

Ultrafast magnetization dynamics in amorphous FeGd alloys — •Raghuveer Chimata — Department of Physics and Astronomy, Uppsala University, Box-516 Uppsala

In recent years, there has been an intense interest in understanding the microscopic mechanism of thermally induced magnetization switching driven by a femtosecond(fs) laser pulse. Most of the efforts have been dedicated to periodic crystalline structures while the amorphous counterparts have been less studied. By using a multiscale approach, i.e. first-principles density functional theory combined with atomistic spin dynamics, we report here on the very intricate structural and magnetic nature of amorphous Gd-Fe alloys for a wide range of Gd and Fe atomic concentrations at the nanoscale level. Both structural and dynamical properties of Gd-Fe alloys reported in this work are in good agreement with previous experiments. We calculated the dynamic behavior of homogeneous and inhomogeneous amorphous Gd-Fe alloys and their response under the influence of a fs laser pulse. In the homogeneous sample, the Fe sublattice switches its magnetization before the Gd one. However the switching process is reversed in the inhomogeneous sample. Furthermore, our results point out that a microscopic mechanism for all-thermal switching does not need to involve spin current effects.