  We have developed 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 $2p\to3d$ absorption of transition metals and $3d\to4f$
absorption of rare earths. Element-specific carrier and valence plasmons can be
observed by using the resonance enhancement of core absorptions. Spin-resolved
plasmons were also observed using a spin-polarized electron source from a
GaAs/GaAsP strained superlattice photocathode. Furthermore, this primary energy
corresponds to an electron penetration depth of 1 to 10 nm and thus provides
bulk-sensitive EELS spectra. The methodology is expected to complement the
element-selective observation of elementary excitations by resonant inelastic
x-ray scattering and resonant photoelectron spectroscopy.
