Interlayer magnetism in Fe3-xGeTe2

TL;DR

This paper investigates the interlayer magnetic ordering in Fe3-xGeTe2, revealing ferromagnetic coupling through experimental and theoretical methods, and emphasizes the importance of Hubbard U corrections in modeling its properties.

Contribution

The study combines neutron diffraction, STM, and DFT+U calculations to clarify the interlayer magnetic order in Fe3-xGeTe2, resolving previous conflicting reports.

Findings

Layers are coupled ferromagnetically

Hubbard U corrections are essential in DFT modeling

Experimental evidence supports ferromagnetic interlayer coupling

Abstract

Fe$_{3-x}$GeTe$_2$ is a layered van der Waals magnetic material with a relatively high ordering temperature and large anisotropy. While most studies have concluded the interlayer ordering to be ferromagnetic, there have also been reports of interlayer antiferromagnetism in Fe$_{3-x}$GeTe$_2$. Here, we investigate the interlayer magnetic ordering by neutron diffraction experiments, scanning tunneling microscopy (STM) and spin-polarized STM measurements, density functional theory plus U calculations and STM simulations. We conclude that the layers of Fe$_{3-x}$GeTe$_2$ are coupled ferromagnetically and that in order to capture the magnetic and electronic properties of Fe$_{3-x}$GeTe$_2$ within density functional theory, Hubbard U corrections need to be taken into account.