We investigated ultrafast demagnetization for NM/Ni80Fe 20 (Py)/NM (NM=Ta,Pt) and epitaxial half-metallic Co2MnSi (CMS) films using an all-optical pump-probe technique to clarify the correlation between demagnetization time τM and magnetic damping constant α or spin polarization. The signal from the all-optical time-resolved magneto-optical Kerr effect exhibited rapid decrease in the sub-ps time regime and damped oscillations for these films. Values of τM and α were evaluated using the three- temperature model and the Landau-Lifshitz- Gilbert equation. The α values for the NM/Py/NM films depended on both the Py thickness and NM materials while τM was almost constant. The τM values for the epitaxial CMS films were almost independent of L21-ordering and a little shorter than those for NM/Py/NM films.
ASJC Scopus subject areas
- Physics and Astronomy(all)