FEMTOSPIN - Multiscale Modelling of Femtosecond Spin Dynamics
- FB Physik
|(2017): Role of temperature-dependent spin model parameters in ultra-fast magnetization dynamics Journal of Physics : Condensed Matter ; 29 (2017), 31. - 314003. - ISSN 0953-8984. - eISSN 1361-648X|
In the spirit of multiscale modelling magnetization dynamics at elevated temperature is often simulated in terms of a spin model where the model parameters are derived from first principles. While these parameters are mostly assumed temperatureindependent and thermal properties arise from spin fluctuations only, other scenarios are also possible. Choosing bcc Fe as an example, we investigate the influence of different kinds of model assumptions on ultra fast spin dynamics, where following a femtosecond laser pulse, a sample is demagnetized due to a sudden rise of the electron temperature. While different model assumptions do not affect the simulational results qualitatively, their details do depend on the nature of the modelling.
|(2015): Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys Physical Review B ; 92 (2015), 5. - 054412. - ISSN 1098-0121. - eISSN 1095-3795|
A hierarchical multiscale approach to model the magnetization dynamics of ferromagnetic random alloys is presented. First-principles calculations of the Heisenberg exchange integrals are linked to atomistic spin models based upon the stochastic Landau-Lifshitz-Gilbert (LLG) equation to calculate temperature-dependent parameters (e.g., effective exchange interactions, damping parameters). These parameters are subsequently used in the Landau-Lifshitz-Bloch (LLB) model for multisublattice magnets to calculate numerically and analytically the ultrafast demagnetization times. The developed multiscale method is applied here to FeNi (permalloy) as well as to copper-doped FeNi alloys. We find that after an ultrafast heat pulse the Ni sublattice demagnetizes faster than the Fe sublattice for the here-studied FeNi-based alloys.
|Sonstige EU||525/12||keine Angabe|
|Laufzeit:||01.06.2012 – 31.05.2015|