Exchange bias in molecule/Fe3GeTe2 van der Waals heterostructures via spinterface effects

TL;DR

This study demonstrates that molecular functionalization with Co-phthalocyanine induces a significant exchange bias in Fe3GeTe2 van der Waals heterostructures, revealing a new way to tailor magnetic properties at the atomic scale.

Contribution

It is the first to explore spinterface effects in layered magnetic materials, showing molecular layers can induce exchange bias in Fe3GeTe2.

Findings

Molecular layer induces exchange bias in Fe3GeTe2

Exchange bias field reaches -840 Oe at 20 nm thickness

Effect persists up to approximately 110 K

Abstract

The exfoliation of layered magnetic materials generates atomically thin flakes characterized by an ultrahigh surface sensitivity, which makes their magnetic properties tunable via external stimuli, such as electrostatic gating and proximity effects. Another powerful approach to tailor magnetic materials is molecular functionalization, which leads to hybrid interface states with peculiar magnetic properties, called spinterfaces. However, spinterface effects have not yet been explored on layered magnetic materials. Here, we demonstrate the emergence of spinterface effects at the interface between flakes of the prototypical layered magnetic metal Fe3GeTe2 and thin films of paramagnetic Co-phthalocyanine. Magnetotransport measurements show that the molecular layer induces a magnetic exchange bias in Fe3GeTe2, indicating that the unpaired spins in Co-phthalocyanine develop antiferromagnetic ordering by proximity and pin the magnetization reversal of Fe3GeTe2. The effect is strongest for a Fe3GeTe2 thickness of 20 nm, for which the exchange bias field reaches -840 Oe and is measurable up to approximately 110 K. This value compares very favorably with previous exchange bias fields reported for Fe3GeTe2 in all-inorganic van der Waals heterostructures, demonstrating the potential of molecular functionalization to tailor the magnetism of van der Waals layered materials.