Relating spin-polarized STM imaging and inelastic neutron scattering in the van-der-Waals ferromagnet Fe3GeTe2

TL;DR

This study combines spin-polarized STM, neutron scattering, and DFT calculations to elucidate the microscopic magnetic and electronic properties of Fe3GeTe2, a van-der-Waals ferromagnet, revealing the relationship between domain wall characteristics and magnon dispersion.

Contribution

It uniquely correlates atomic-scale magnetic imaging with neutron scattering data to understand the microscopic magnetic properties of Fe3GeTe2, advancing spintronics material design.

Findings

Excellent agreement between domain wall width and magnon dispersion measurements.

Quasi-particle interference dominated by spin-majority bands.

Dimensional dichotomy of bands at the Fermi energy with minority bands being 2D and majority bands 3D.

Abstract

Van-der-Waals (vdW) ferromagnets have enabled the development of heterostructures assembled from exfoliated monolayers with spintronics functionalities, making it important to understand and ultimately tune their magnetic properties at the microscopic level. Information about the magnetic properties of these systems comes so far largely from macroscopic techniques, with little being known about the microscopic magnetic properties. Here, we combine spin-polarized scanning tunneling microscopy and quasi-particle interference imaging with neutron scattering to establish the magnetic and electronic properties of the metallic vdW ferromagnet Fe3GeTe2. By imaging domain walls at the atomic scale, we can relate the domain wall width to the exchange interaction and magnetic anisotropy extracted from the magnon dispersion as measured in inelastic neutron scattering, with excellent agreement between the two techniques. From comparison with Density Functional Theory calculations we can assign the quasi-particle interference to be dominated by spin-majority bands. We find a dimensional dichotomy of the bands at the Fermi energy: bands of minority character are predominantly two-dimensional in character, whereas the bands of majority character are three-dimensional. We expect that this will enable new design principles for spintronics devices.