Theory of momentum-resolved magnon electron energy loss spectra: The case of Yttrium Iron Garnet

TL;DR

This paper develops a theoretical framework for analyzing momentum-resolved magnon-electron energy loss spectra in magnetic materials, exemplified by Yttrium Iron Garnet, highlighting charge interactions and scattering vector dependencies.

Contribution

It introduces a novel theoretical approach to interpret inelastic electron spectra in magnetic systems, emphasizing charge interactions and vector potential effects.

Findings

Charge-dependent interaction is about 1% of spin interaction.

Strong scattering vector dependence with a $oldsymbol{ ext{ extkappa}}^{-4}$ behavior.

Interaction depends on the orientation between probe wavevector and magnetic moments.

Abstract

We explore the inelastic spectra of electrons impinging in a magnetic system. The methodology here presented is intended to highlight the charge-dependent interaction of the electron beam in a STEM-EELS experiment, and the local vector potential generated by the magnetic lattice. This interaction shows an intensity $10^{-2}$ smaller than the purely spin interaction, which is taken to be functionally the same as in the inelastic neutron experiment. On the other hand, it shows a strong scattering vector dependence ($\kappa^{-4}$) and a dependence with the relative orientation between the probe wavevector and the local magnetic moments of the solid. We present YIG as a case study due to its high interest by the community.