Quantification of a propagating spin-wave-packet created by an   ultrashort laser pulse in a thin film of magnetic metal
  Coherent spin-wave generation by focused ultrashort laser pulse irradiation was investigated for a permalloy thin film at micrometer scale using an all-optical space and time-resolved magneto-optical Kerr effect. The spin-wave packet propagating perpendicular to magnetization direction was clearly observed, however that propagating parallel to the magnetization direction was not observed. The propagation length, group velocity, center frequency, and packet-width of the observed spin-wave packet were evaluated and quantitatively explained in terms of the propagation of a magneto-static spin-wave driven by ultrafast change of an out-of-plane demagnetization field induced by the focused-pulse laser. 
S. Iihama, Y. Sasaki, A. Sugihara, A. Kamimaki, Y. Ando, and S.   Mizukami
cond-mat.mes-hall