Anatomy and giant enhancement of the perpendicular magnetic anisotropy of cobalt-graphene heterostructures

TL;DR

This paper demonstrates that coating cobalt films with graphene significantly enhances their perpendicular magnetic anisotropy, supported by first-principles calculations and experiments, with implications for advanced spintronic devices.

Contribution

It reveals that graphene can dramatically boost Co film anisotropy and extends the effective anisotropy thickness, providing insights for designing heterostructures with giant magnetic anisotropy.

Findings

Graphene coating doubles surface anisotropy of Co films.

Enhanced anisotropy extends up to 25 Å thickness.

Proposed Co-graphene heterostructures with stable out-of-plane anisotropy.

Abstract

We report strongly enhanced perpendicular magnetic anisotropy (PMA) of Co films by graphene coating from both first-principles and experiments. Our calculations show that graphene can dramatically boost the surface anisotropy of Co films up to twice the value of its pristine counterpart and can extend the out-of-plane effective anisotropy up to unprecedented thickness of 25~\AA. These findings are supported by our experiments on graphene coating on Co films grown on Ir substrate. Furthermore, we report layer-resolved and orbital-hybridization-resolved anisotropy analysis which help understanding the physical mechanisms of PMA and more practically can help design structures with giant PMA. As an example, we propose super-exchange stabilized Co-graphene heterostructures with a robust out-of-plane constant effective PMA and linearly increasing interfacial anisotropy as a function of film thickness. These findings point towards possibilities to engineer graphene/ferromagnetic metal heterostructures with giant magnetic anisotropy more than 20 times larger compared to conventional multilayers, which constitutes a hallmark for future graphene and traditional spintronic technologies.