Magnetic properties of CoFeB films grown on a single-layer graphene underlayer

Associating thin ferromagnetic (FM) films with two-dimensional (2D) materials appears to be a promising approach for the next-generation spintronic devices. Consequently, the control of the magnetic phenomena in the FM/2D systems is of the utmost importance. We investigate in this paper the structural, static, and dynamic magnetic properties of $\mathrm{Si}{O}_2/\mathrm{single}-\mathrm{layer}$ graphene (SLG)/CoFeB ($3\mathrm{nm}\le t_{\mathrm{CFB}}\le 20\mathrm{nm})/\mathrm{Cu}$ (3 nm) structures and compared them with control samples, without the SLG underlayer. The single-layer characteristics of the synthesized graphene are deduced from Raman spectroscopy investigations. Vibrating sample magnetometry measurements allowed deducting the magnetization at saturation $M_s$, the coercive field $H_c$, and the magnetic dead layer thickness $t_d$. In the absence of SLG, the nominal thickness $t_{\mathrm{CFB}}$ is almost preserved, while $t_d\approx 2\mathrm{nm}$ was determined in presence of graphene. Here, $H_c$ was found to increase in presence of SLG compared with the control structures, while $M_s$ are comparable. Brillouin light scattering and microstrip FM resonance measurements were employed to investigate the dynamic magnetic properties of the samples. It was found that the magnetic anisotropy results from interface and volume contributions and that the largest interface anisotropy was observed in presence of SLG. Measurements of the spin waves nonreciprocity, related to the interfacial Dzyloshinskii-Moriya interaction (iDMI), revealed weak iDMI in our samples. The magnetic damping in the SLG/CFB films was found to be dominated by the two-magnon contribution. No spin pumping was observed either without or with graphene. Our results highlight the influence of the graphene ripples on the magnetic properties of graphene/FM-based heterostructures.