Van der Waals (vdW) heterostructures allow the engineering of electronic and magnetic properties by the stacking different two-dimensional vdW materials. For example, orbital hybridisation and charge transfer at a vdW interface may result in electric fields across the interface that give rise to Rashba spin-orbit coupling. In magnetic vdW heterostructures, this in turn can drive the Dzyaloshinskii-Moriya interaction which leads to a canting of local magnetic moments at the vdW interface and may thus stabilise novel 2D magnetic phases. While such emergent magnetic "interphases" offer a promising platform for spin-based electronics, direct spectroscopic evidence for them is still lacking. Here, we report Zeeman effects with Land\'e g-factors up to ≈230 at the interface of graphene and the vdW ferromagnet Fe3GeTe2. They arise from a magnetic interphase in which local-moment canting and itinerant orbital moments generated by the non-trivial band topology of Fe3GeTe2 conspire to cause a giant asymmetric level splitting when a magnetic field is applied. Exploiting the inelastic phonon gap of graphene, we can directly access the buried vdW interface to the Fe3GeTe2 by scanning tunnelling spectroscopy. Systematically analyzing the Faraday-like screening of the tip electric field by the graphene, we demonstrate the tunability of the constitutional interface dipole, as well as the Zeeman effect, by tip gating. Our findings are supported by density functional theory and electrostatic modelling.
@article{arxiv.2510.26662,
title = {Giant orbital Zeeman effects in a magnetic topological van der Waals interphase},
author = {Tobias Wichmann and Mirco Sastges and Keda Jin and Jose Martinez-Castro and Tom G. Saunderson and Dongwook Go and Honey Boban and Samir Lounis and Lukasz Plucinski and Markus Ternes and Yuriy Mokrousov and F. Stefan Tautz and Felix Lüpke},
journal= {arXiv preprint arXiv:2510.26662},
year = {2025}
}