Bulk-Sensitive Spin-Resolved Resonant Electron Energy-Loss Spectroscopy (SR-rEELS): Observation of Element- and Spin-Selective Bulk Plasmons

TL;DR

This paper introduces a novel spin-resolved resonant electron energy-loss spectroscopy technique that enables element- and spin-specific detection of bulk plasmons with high energy resolution, providing new insights into elementary excitations.

Contribution

The development of SR-rEELS with 0.3-1.5 keV primary energy allows element- and spin-selective bulk plasmon observation using resonance enhancement and spin polarization.

Findings

Element- and spin-selective bulk plasmons observed

Resonance enhancement improves elemental sensitivity

Bulk sensitivity achieved with 1-10 nm mean free path

Abstract

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.