Quantum Oscillations of Gilbert Damping in Ferromagnetic/Graphene Bilayer Systems

TL;DR

This paper demonstrates that the Gilbert damping in ferromagnetic/graphene bilayers oscillates with magnetic field due to Landau levels, enabling probing of graphene's electronic structure via ferromagnetic resonance.

Contribution

It introduces a theoretical model linking Gilbert damping oscillations to graphene's Landau levels and exchange coupling, providing a new method to analyze spin-resolved electronic structures.

Findings

Gilbert damping is enhanced by proximity exchange coupling.

Damping oscillates with magnetic field due to graphene Landau levels.

Oscillation period reveals exchange coupling strength.

Abstract

We study the spin dynamics of a ferromagnetic insulator on which graphene is placed. We show that the Gilbert damping is enhanced by the proximity exchange coupling at the interface. The modulation of the Gilbert damping constant is proportional to the product of the spin-up and spin-down densities of states of graphene. Consequently, the Gilbert damping constant in a strong magnetic field oscillates as a function of the external magnetic field that originates from the Landau level structure of graphene. We find that a measurement of the oscillation period enables the strength of the exchange coupling constant to be determined. The results demonstrate in theory that the ferromagnetic resonance measurements may be used to detect the spin resolved electronic structure of the adjacent materials, which is critically important for future spin device evaluations.