Suppression of Spin Pumping Between Ni$_{80}$Fe$_{20}$ and Cu by a Graphene Interlayer

TL;DR

This study demonstrates that a graphene interlayer effectively suppresses spin pumping between Ni80Fe20 and Cu, attributed to high contact resistance at the graphene/copper interface, as shown by ferromagnetic resonance measurements.

Contribution

The paper provides experimental evidence that a graphene interlayer can suppress spin pumping in ferromagnetic/metal systems, highlighting the role of interface contact resistance.

Findings

No detectable spin pumping with graphene interlayer

Damping enhancement observed without graphene

Magnetometry confirms magnetostatic properties are unchanged

Abstract

We compare ferromagnetic resonance measurements of Permalloy Ni$_{80}$Fe$_{20}$ (Py) films sputtered onto Cu(111) films with and without a graphene (Gr) interlayer grown by chemical vapor deposition before Py deposition. A two-angle sputtering method ensured that neither Gr nor Py was degraded by the sample preparation process. We find the expected damping enhancement from spin pumping for the Py/Cu case and no detectable enhancement for the Py/Gr/Cu case. Since damping is sensitive to effects other than spin pumping, we used magnetometry to verify that differences in Py magnetostatic properties are not responsible for the difference in damping. We attribute the suppression of spin pumping in Py/Gr/Cu to the large contact resistance of the Gr/Cu interface.