  Using a magneto-optical pump-probe technique with micrometer spatial
resolution we show that magnetization precession can be launched in individual
magnetic domains imprinted in a Co$_{40}$Fe$_{40}$B$_{20}$ (CoFeB) layer by
elastic coupling to ferroelectric domains in a BaTiO$_{3}$ substrate. The
dependence of the precession parameters on external magnetic field strength and
orientation reveal that by laser-induced ultrafast partial quenching of the
magnetoelastic coupling parameter of CoFeB by $\approx$27% along with 10%
ultrafast demagnetization trigger the magnetization precession. The relation
between the laser-induced reduction of the magnetoelastic coupling and the
demagnetization is approximated by the $n(n+1)/2$-law with n$\approx$2. This
correspondence confirms the thermal origin of the laser-induced anisotropy
change. Based on the analysis and modeling of the excited precession we find
signatures of laser-induced precessional switching, which occurs when the
magnetic field is applied along the hard magnetization axis and its value is
close to the effective magnetoelastic anisotropy field. The precession
excitation process in an individual magnetoelastic domain is found to be
unaffected by neighboring domains. This makes laser-induced changes of
magnetoelastic anisotropy a promising tool for driving magnetization dynamics
and switching in composite multiferroics with spatial selectivity.
