  We have developed a spin-resolved resonant electron energy-loss spectroscopy
(SR-rEELS) in the primary energy of 0.3--1.5 keV, which corresponds to the core
excitations of $2p$-$3d$ absorption of transition metals and $3d$-$4f$
absorption of rare-earths, with the energy resolution of about 100~meV using a
spin-polarized electron source as a GaAs/GaAsP strained superlattice
photocathode. Element- and spin-selective carrier and valence plasmons can be
observed using the resonance enhancement of core absorptions and electron spin
polarization. Furthermore, bulk-sensitive EELS spectra can be obtained because
the primary energy corresponds to the mean free path of 1--10~nm. The
methodology is expected to provide us novel information of elementary
excitations by resonant inelastic x-ray scattering and resonant photoelectron
spectroscopy.
