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Ultrafast demagnetization for Ni 80 Fe 20 and half-metallic Co 2 MnSi heusler alloy films

2010; IOP Publishing; Volume: 200; Issue: 4 Linguagem: Inglês

10.1088/1742-6596/200/4/042017

1742-6596

Shigemi Mizukami, Sumito Tsunegi, Takahide Kubota, Mikihiko Oogane, Daisuke Watanabe, Hiroshi Naganuma, Yasuo Ando, T. Miyazaki,

Magnetic Properties and Applications

We investigated ultrafast demagnetization for NM/Ni80Fe20 (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.